The average (arithmetic mean) age of a group of doctors and lawyers is 40. If the doctors average 35 years of age and the lawyers average 50 years of age, then the ratio of the number of doctors to the number of lawyers is:

- 3:2
- 3:1
- 2:3
- 2:1
- 1:2

Let’s have *D* doctors. If their average age is 35, the total of their ages is 35*D*. And for *L* lawyers, the total of their ages is 50*L*. The average for all of them is 40:

(35

35

35

50

10

*D*+ 50*L*) / (*D*+*L*) = 4035

*D*+ 50*L*= 40(*D*+*L*)35

*D*+ 50*L*= 40*D*+ 40*L*50

*L*– 40*L*= 40*D*– 35*D*10

*L*= 5*D*=> 10/5 =*D*/*L*= 2:1The answer is d.