The GPA for a class of ten females and seven males are recorded. The mean GPA of females is 3.07 and the standard deviation is 0.53. The mean GPA for males is also 3.07 and the standard deviation is 0.68. What is standard the deviation for all students ?

Attempt to solution:

Girls

or

Boys

or

Guys l am stuck here. It seems like l am in a vicious cycle. What should l do ?