Question

Pleeeeeeeeeeeeease help !!

Answer 1

first convert x into z
z = (x-u)/s, where u = mean, and s = SD
z = (5-10)/7
z = -0.71

let k be the z-score for c. Then
P(k) - P(-0.71) = 0.3
P(k) - 0.2389 = 0.3
P(k) = 0.5389
k = 0.1

0.1 = (c-5)/7
c = 5.7

Answer 2

it's because it's given that 5 < x < c, so 5 is one of the x's