Question

a well know standard i.q test produces normally distributed results with a mean of 100 and a standard deviation of 15. What percent of the population have an i.q between 91 and 109

Answer 1

اوکم we have mean u = loo standard deviation o = 15 here, a, al + 242 = 109 z = 4 Z2 = -ll * = 91 - 100 Zz = 109 – 100 15 15 Z = -0.6 Z = 0.6 Now, Plz & Z <22) P(-0.6 20.6) P(Z < 0.6) - P(Z < -0.6) 0. 1251 -0.2743 t from ene z-table 0.4514 = 0.4514 X 100)% = 45.14% They fou, 45.14% of the population have an I-a between 91 and 109.