Question

please answer part D

A simple random sample of size n=81 is obtained from a population with u = 73 and 6 = 36. (a) Describe the sampling distribution of x. (b) What is P (x>77.6) ? (c) What is P (*s65)? (d) What is P (70.4<x<81)? πια τι ειναι μια οιαιααιααυνιααοιι υιιυ υμνημης αισιναταοιιυι Α. = 73 x = = 4 (b)P (X>77.6) = 1251 (Round to four decimal places as needed.) (c) P (X365) = .0228 (Round to four decimal places as needed.) (d) P (70.4 << <81) = (Round to four decimal places as needed.)

Answer 1

Ans d) 0.7194

Explanation:

Formula to calculate z-score:

$z = \frac{\bar{x}-\mu}{\sigma_{\bar{x}}}$

$P(70.4<\bar{x}<81) = P(Z < \frac{81-73}{4})-P(Z < \frac{70.4-73}{4})$

$=0.9772-0.2578$

$=0.7194$ ans.

/* we can find probability using excel function: =NORM.S.DIST(2,TRUE) */