NATABERI wrote:

An investor can sell her MicroTron stock for 36$ per share and her Dynaco stock for 52$ per share, If she sells 300 shares altogether, some of each stock, at an average price per share of 40$, how many shares of Dynaco stock has she sold?

A) 52

B) 75

C) 92

D) 136

E) 184

Hi,

yeah, this one can be solved quicky using the weighted average approach.

Avg = 40 $

MicroTron stock = 36$

Dynaco stock = 52$

Arrange this on a number line for clarity:

36----40------------52

Note:Notice the average is closer to 36$. So that means there will be more no. of MicroTron stocks sold.

According to to the weighted average approach, the ratio of the quantities will be opposite of the distance from the avergae i.e. ratio of MicroTron stock : Dynaco stock = 12:4

Now solve it as a ratio problem.

Lets say the unknown multiplier is 'x'

so we have 12x + 4x = 300

x = 75/4

Therefore 4x = 4 * (75/4) = 75.

For more information on weighted averages, check out the quants link below:

consolodited-quant-guides-of-forum-most-helpful-in-preps-151067.html#p1217652Thanks!