25 writers, 20 doctors, 18 dentists and 12 bank employees spent altoge

25 writers, 20 doctors, 18 dentists and 12 bank employees spent altogether ₹ 1,330 in a hotel. However, it was found that 5 writers spent as much as 4 doctors, that 12 doctors spent as much as 9 dentists, and that 6 dentists spent as much as 8 bank employees. Out of the four professional groups, which group spent the maximum amount ?

Bank employees
Dentists
Doctors
Writers
This question was previously asked in
UPSC CISF-AC-EXE – 2018
The correct answer is B) Dentists.
Let $w_s, d_s, t_s, b_s$ be the average amount spent by one writer, doctor, dentist, and bank employee, respectively. The number of people in each group is 25 writers, 20 doctors, 18 dentists, and 12 bank employees.
We are given the following relationships:
1. 5 writers spend as much as 4 doctors: $5w_s = 4d_s \implies w_s = \frac{4}{5}d_s$
2. 12 doctors spend as much as 9 dentists: $12d_s = 9t_s \implies 4d_s = 3t_s \implies t_s = \frac{4}{3}d_s$
3. 6 dentists spend as much as 8 bank employees: $6t_s = 8b_s \implies 3t_s = 4b_s$
Substitute $t_s$ from (2) into (3): $3(\frac{4}{3}d_s) = 4b_s \implies 4d_s = 4b_s \implies d_s = b_s$
So, we have $w_s = \frac{4}{5}d_s$, $t_s = \frac{4}{3}d_s$, and $b_s = d_s$.
The total amount spent is ₹ 1330: $25w_s + 20d_s + 18t_s + 12b_s = 1330$
Substitute the values in terms of $d_s$: $25(\frac{4}{5}d_s) + 20d_s + 18(\frac{4}{3}d_s) + 12d_s = 1330$
$20d_s + 20d_s + 24d_s + 12d_s = 1330$
$76d_s = 1330 \implies d_s = \frac{1330}{76} = 17.5$
Now calculate the amount spent per person for each group:
$d_s = 17.5$
$w_s = \frac{4}{5} \times 17.5 = 14$
$t_s = \frac{4}{3} \times 17.5 = \frac{70}{3} \approx 23.33$
$b_s = 17.5$
Total amount spent by each group:
Writers: $25 \times 14 = 350$
Doctors: $20 \times 17.5 = 350$
Dentists: $18 \times \frac{70}{3} = 6 \times 70 = 420$
Bank Employees: $12 \times 17.5 = 210$
Comparing the total amounts, the Dentists group spent the maximum amount (₹ 420).
This problem requires setting up equations based on the given relationships and solving for the per-person cost of one group, then using that to find the costs for others and finally the total expenditure per group.