Answer:
d. S.D= 7.3
Step-by-step explanation:
x f f(x) x² f(x²)
75 2 150 5625 11250
80 3 240 6400 19200
85 2 170 7225 14450
90 2 180 8100 16200
95 0 0 9025 0
100 1 100 10000 10000
Sum f= 10 fx= 840 f(x²) = 71,100
Standard Deviation = √Sum fx² - (Sum f(x))²/sum f/ f
S.D= √71,100- (840)²/10/10
S.D= √71,100- 70560/10
S.D= √540/10
S.D= √54
S.D= 7.348 ≅7.3
