Homework SourseA comprehensive study of stress during pregnancy is conducte
A comprehensive study of stress during pregnancy is conducted in every hospital in New Zealand. A scale called the Pregnancy Stress Scale is given to all pregnant women. The mean (?) of the scale is 55 and the standard deviation (?) is 10. Assuming that the scores are normally distributed, what PERCENTAGE of the population falls between 75 and 46?
Solution
= 79.31%
| mean = 55 |
| Std Dev (s) =10 |
| Find : P( 46 < X < 75 ) We convert to standard normal form, by z = (x - u )/s so z1 = (46 - 55 )/10 = -0.9 & z2 = (75 - 55 )/10 = 2 P( 46 < X < 75) = P(z1 < Z < z2) = P( Z < 2) - P(Z < -0.9) = 0.9772 - 0.1841 = 0.7931 _ _ _ _ _ _ _ _ _ (From Z-table) |
