{"id":93222,"date":"2025-06-01T11:45:18","date_gmt":"2025-06-01T11:45:18","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=93222"},"modified":"2025-06-01T11:45:18","modified_gmt":"2025-06-01T11:45:18","slug":"in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/","title":{"rendered":"In a swimming competition, the players were asked to swim 9 km upstrea"},"content":{"rendered":"

In a swimming competition, the players were asked to swim 9 km upstream and then swim back to the point of starting. The winner of the competition could complete the task in 1 hour and 30 minutes. If the speed of the current of the river water was 8 km\/hr, the speed of the winner is :<\/p>\n

[amp_mcq option1=”16 km\/hr” option2=”20 km\/hr” option3=”14 km\/hr” option4=”18 km\/hr” correct=”option1″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC CISF-AC-EXE – 2023<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nThe correct answer is 16 km\/hr. This is the speed of the winner (swimmer) in still water, calculated based on the total time taken for the upstream and downstream journey.
\n<\/section>\n
\n– Let the speed of the swimmer in still water be ‘s’ km\/hr.
\n– Speed of the current = 8 km\/hr.
\n– Upstream speed (against the current) = (s – 8) km\/hr.
\n– Downstream speed (with the current) = (s + 8) km\/hr.
\n– Distance upstream = 9 km.
\n– Distance downstream = 9 km.
\n– Total time = 1 hour 30 minutes = 1.5 hours.
\n– Time upstream = Distance \/ Upstream speed = 9 \/ (s – 8) hours.
\n– Time downstream = Distance \/ Downstream speed = 9 \/ (s + 8) hours.
\n– Total time equation: 9\/(s – 8) + 9\/(s + 8) = 1.5
\n– Multiply the equation by (s – 8)(s + 8): 9(s + 8) + 9(s – 8) = 1.5(s – 8)(s + 8)
\n– 9s + 72 + 9s – 72 = 1.5(s\u00b2 – 64)
\n– 18s = 1.5s\u00b2 – 96
\n– Multiply by 2: 36s = 3s\u00b2 – 192
\n– Divide by 3: 12s = s\u00b2 – 64
\n– Rearrange into a quadratic equation: s\u00b2 – 12s – 64 = 0
\n– Factor the equation: (s – 16)(s + 4) = 0
\n– Possible values for s are 16 or -4. Since speed must be positive, s = 16 km\/hr.
\n– The speed of the swimmer (16 km\/hr) must be greater than the speed of the current (8 km\/hr) for upstream movement to be possible, which is true (16 > 8).
\n<\/section>\n
\nThis is a standard ‘boats and streams’ problem. The crucial concepts are how the speed of the current affects the speed of the swimmer (or boat) upstream and downstream, and setting up the equation based on the total time taken for the round trip.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

In a swimming competition, the players were asked to swim 9 km upstream and then swim back to the point of starting. The winner of the competition could complete the task in 1 hour and 30 minutes. If the speed of the current of the river water was 8 km\/hr, the speed of the winner … <\/p>\n

Detailed SolutionIn a swimming competition, the players were asked to swim 9 km upstrea<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1089],"tags":[1105,1102],"class_list":["post-93222","post","type-post","status-publish","format-standard","hentry","category-upsc-cisf-ac-exe","tag-1105","tag-quantitative-aptitude-and-reasoning","no-featured-image-padding"],"yoast_head":"\nIn a swimming competition, the players were asked to swim 9 km upstrea<\/title>\n<meta name=\"description\" content=\"The correct answer is 16 km\/hr. This is the speed of the winner (swimmer) in still water, calculated based on the total time taken for the upstream and downstream journey. - Let the speed of the swimmer in still water be 's' km\/hr. - Speed of the current = 8 km\/hr. - Upstream speed (against the current) = (s - 8) km\/hr. - Downstream speed (with the current) = (s + 8) km\/hr. - Distance upstream = 9 km. - Distance downstream = 9 km. - Total time = 1 hour 30 minutes = 1.5 hours. - Time upstream = Distance \/ Upstream speed = 9 \/ (s - 8) hours. - Time downstream = Distance \/ Downstream speed = 9 \/ (s + 8) hours. - Total time equation: 9\/(s - 8) + 9\/(s + 8) = 1.5 - Multiply the equation by (s - 8)(s + 8): 9(s + 8) + 9(s - 8) = 1.5(s - 8)(s + 8) - 9s + 72 + 9s - 72 = 1.5(s\u00b2 - 64) - 18s = 1.5s\u00b2 - 96 - Multiply by 2: 36s = 3s\u00b2 - 192 - Divide by 3: 12s = s\u00b2 - 64 - Rearrange into a quadratic equation: s\u00b2 - 12s - 64 = 0 - Factor the equation: (s - 16)(s + 4) = 0 - Possible values for s are 16 or -4. Since speed must be positive, s = 16 km\/hr. - The speed of the swimmer (16 km\/hr) must be greater than the speed of the current (8 km\/hr) for upstream movement to be possible, which is true (16 > 8).\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"In a swimming competition, the players were asked to swim 9 km upstrea\" \/>\n<meta property=\"og:description\" content=\"The correct answer is 16 km\/hr. This is the speed of the winner (swimmer) in still water, calculated based on the total time taken for the upstream and downstream journey. - Let the speed of the swimmer in still water be 's' km\/hr. - Speed of the current = 8 km\/hr. - Upstream speed (against the current) = (s - 8) km\/hr. - Downstream speed (with the current) = (s + 8) km\/hr. - Distance upstream = 9 km. - Distance downstream = 9 km. - Total time = 1 hour 30 minutes = 1.5 hours. - Time upstream = Distance \/ Upstream speed = 9 \/ (s - 8) hours. - Time downstream = Distance \/ Downstream speed = 9 \/ (s + 8) hours. - Total time equation: 9\/(s - 8) + 9\/(s + 8) = 1.5 - Multiply the equation by (s - 8)(s + 8): 9(s + 8) + 9(s - 8) = 1.5(s - 8)(s + 8) - 9s + 72 + 9s - 72 = 1.5(s\u00b2 - 64) - 18s = 1.5s\u00b2 - 96 - Multiply by 2: 36s = 3s\u00b2 - 192 - Divide by 3: 12s = s\u00b2 - 64 - Rearrange into a quadratic equation: s\u00b2 - 12s - 64 = 0 - Factor the equation: (s - 16)(s + 4) = 0 - Possible values for s are 16 or -4. Since speed must be positive, s = 16 km\/hr. - The speed of the swimmer (16 km\/hr) must be greater than the speed of the current (8 km\/hr) for upstream movement to be possible, which is true (16 > 8).\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T11:45:18+00:00\" \/>\n<meta name=\"author\" content=\"rawan239\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"rawan239\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"In a swimming competition, the players were asked to swim 9 km upstrea","description":"The correct answer is 16 km\/hr. This is the speed of the winner (swimmer) in still water, calculated based on the total time taken for the upstream and downstream journey. - Let the speed of the swimmer in still water be 's' km\/hr. - Speed of the current = 8 km\/hr. - Upstream speed (against the current) = (s - 8) km\/hr. - Downstream speed (with the current) = (s + 8) km\/hr. - Distance upstream = 9 km. - Distance downstream = 9 km. - Total time = 1 hour 30 minutes = 1.5 hours. - Time upstream = Distance \/ Upstream speed = 9 \/ (s - 8) hours. - Time downstream = Distance \/ Downstream speed = 9 \/ (s + 8) hours. - Total time equation: 9\/(s - 8) + 9\/(s + 8) = 1.5 - Multiply the equation by (s - 8)(s + 8): 9(s + 8) + 9(s - 8) = 1.5(s - 8)(s + 8) - 9s + 72 + 9s - 72 = 1.5(s\u00b2 - 64) - 18s = 1.5s\u00b2 - 96 - Multiply by 2: 36s = 3s\u00b2 - 192 - Divide by 3: 12s = s\u00b2 - 64 - Rearrange into a quadratic equation: s\u00b2 - 12s - 64 = 0 - Factor the equation: (s - 16)(s + 4) = 0 - Possible values for s are 16 or -4. Since speed must be positive, s = 16 km\/hr. - The speed of the swimmer (16 km\/hr) must be greater than the speed of the current (8 km\/hr) for upstream movement to be possible, which is true (16 > 8).","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/","og_locale":"en_US","og_type":"article","og_title":"In a swimming competition, the players were asked to swim 9 km upstrea","og_description":"The correct answer is 16 km\/hr. This is the speed of the winner (swimmer) in still water, calculated based on the total time taken for the upstream and downstream journey. - Let the speed of the swimmer in still water be 's' km\/hr. - Speed of the current = 8 km\/hr. - Upstream speed (against the current) = (s - 8) km\/hr. - Downstream speed (with the current) = (s + 8) km\/hr. - Distance upstream = 9 km. - Distance downstream = 9 km. - Total time = 1 hour 30 minutes = 1.5 hours. - Time upstream = Distance \/ Upstream speed = 9 \/ (s - 8) hours. - Time downstream = Distance \/ Downstream speed = 9 \/ (s + 8) hours. - Total time equation: 9\/(s - 8) + 9\/(s + 8) = 1.5 - Multiply the equation by (s - 8)(s + 8): 9(s + 8) + 9(s - 8) = 1.5(s - 8)(s + 8) - 9s + 72 + 9s - 72 = 1.5(s\u00b2 - 64) - 18s = 1.5s\u00b2 - 96 - Multiply by 2: 36s = 3s\u00b2 - 192 - Divide by 3: 12s = s\u00b2 - 64 - Rearrange into a quadratic equation: s\u00b2 - 12s - 64 = 0 - Factor the equation: (s - 16)(s + 4) = 0 - Possible values for s are 16 or -4. Since speed must be positive, s = 16 km\/hr. - The speed of the swimmer (16 km\/hr) must be greater than the speed of the current (8 km\/hr) for upstream movement to be possible, which is true (16 > 8).","og_url":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T11:45:18+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/","url":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/","name":"In a swimming competition, the players were asked to swim 9 km upstrea","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T11:45:18+00:00","dateModified":"2025-06-01T11:45:18+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"The correct answer is 16 km\/hr. This is the speed of the winner (swimmer) in still water, calculated based on the total time taken for the upstream and downstream journey. - Let the speed of the swimmer in still water be 's' km\/hr. - Speed of the current = 8 km\/hr. - Upstream speed (against the current) = (s - 8) km\/hr. - Downstream speed (with the current) = (s + 8) km\/hr. - Distance upstream = 9 km. - Distance downstream = 9 km. - Total time = 1 hour 30 minutes = 1.5 hours. - Time upstream = Distance \/ Upstream speed = 9 \/ (s - 8) hours. - Time downstream = Distance \/ Downstream speed = 9 \/ (s + 8) hours. - Total time equation: 9\/(s - 8) + 9\/(s + 8) = 1.5 - Multiply the equation by (s - 8)(s + 8): 9(s + 8) + 9(s - 8) = 1.5(s - 8)(s + 8) - 9s + 72 + 9s - 72 = 1.5(s\u00b2 - 64) - 18s = 1.5s\u00b2 - 96 - Multiply by 2: 36s = 3s\u00b2 - 192 - Divide by 3: 12s = s\u00b2 - 64 - Rearrange into a quadratic equation: s\u00b2 - 12s - 64 = 0 - Factor the equation: (s - 16)(s + 4) = 0 - Possible values for s are 16 or -4. Since speed must be positive, s = 16 km\/hr. - The speed of the swimmer (16 km\/hr) must be greater than the speed of the current (8 km\/hr) for upstream movement to be possible, which is true (16 > 8).","breadcrumb":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/exam.pscnotes.com\/mcq\/in-a-swimming-competition-the-players-were-asked-to-swim-9-km-upstrea\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/exam.pscnotes.com\/mcq\/"},{"@type":"ListItem","position":2,"name":"UPSC CISF-AC-EXE","item":"https:\/\/exam.pscnotes.com\/mcq\/category\/upsc-cisf-ac-exe\/"},{"@type":"ListItem","position":3,"name":"In a swimming competition, the players were asked to swim 9 km upstrea"}]},{"@type":"WebSite","@id":"https:\/\/exam.pscnotes.com\/mcq\/#website","url":"https:\/\/exam.pscnotes.com\/mcq\/","name":"MCQ and Quiz for Exams","description":"","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/exam.pscnotes.com\/mcq\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209","name":"rawan239","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","caption":"rawan239"},"sameAs":["https:\/\/exam.pscnotes.com"],"url":"https:\/\/exam.pscnotes.com\/mcq\/author\/rawan239\/"}]}},"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/93222","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/comments?post=93222"}],"version-history":[{"count":0,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/93222\/revisions"}],"wp:attachment":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/media?parent=93222"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/categories?post=93222"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/tags?post=93222"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}