1. ## Statistics

If 36 students took a test. The mean of those who passed was 78. The mean of those who failed is 60. The mean of all scores is 70. How many students failed the test ?

2. Originally Posted by Jhonson
If 36 students took a test. The mean of those who passed was 78. The mean of those who failed is 60. The mean of all scores is 70. How many students failed the test ?
Solve simultaneously:

$78 x_p + 60 x_f = (36)(70)$ .... (1)

$x_p + x_f = 36$ .... (2)