Question 391174
36 students took a test that required a passing grade of 70.
 The mean of those who passed was 78. The mean of those who failed was 60.
 The total mean was 71. How many students failed.
:
Let x = those that failed
then
(36-x) = those that passed
:
{{{(78(36-x) + 60x)/36}}} = 71