Answer is (C) 140
Here's the information that we are given:
Volunteers can be put into one out of the four available groups trainee (t), assistant (a), nurse (n), co-ordinator (c)
The ratio t/a = 3/4
The ratio t/n is 3/4 times t/a, hence t/n = (3/4)*(3/4) = 9/16
The ratio a/c is twice that of t/a, hence a/c = 2*(3/4) = 6/4
Combined number of t and c is less than the smallest three digit positive integer with unique digits ==> the smallest three digit positive integer is 100. But here, 0 repeats. So we go to 101. Here 1 repeats. Thus, we go to 102 (which is what we need)
Therefore, t+c < 102
Now, let's try and find the common ratio of all 4 numbers.
t/a = 3/4 ==> t = (3/4)a
thus, a/t= 4/3 = 12/9
t/n = 9/16 ===> t = (9/16)n
Thus, a:t:n = 12:9:16
Also, a/c = 6/4 = 12/8
Thus, a:t:n:c = 12:9:16:8
Let x be the common factor of the ratio.
Thus,
a = 12x
t = 9x
n = 16x
c = 8x
Now, we are given that, t+c < 102
Thus, 9x+8x < 102
17x < 102
x<6
Now, for the number of people to be whole numbers, x has to be an integer. For us to find the maximum number of a+n , x has to be the largest possible integer less than 6 i.e. 5
Thus a+n = 12x+16x = 12*5+16*5 = 60+80 = 140