# (solution) SHOW WORK PLEASE, I WANT TO KNOW HOW TO DO IT. 6. A calculus exam

SHOW WORK PLEASE, I WANT TO KNOW HOW TO DO IT.

6. A calculus exam had a mean of 75 and a

standard deviation of 6. If Sally had made a 78

on this exam, what is her z-score?

16. Find the following probabilities:

a. P(Z < ?1.82)

b. P(?1.68 < Z < 2.09)

c. P(Z > 0.56)

d. P(?0.52 < Z < 0.52)

e. P(?2.09 < Z <1.32)

f. P(Z > ?1.08)

18. Find the value of c that satisfies each of the

following probabilities:

a. P(Z < c) = 0.0495

b. P(Z < c) = 0.8438

c. P(Z > c) = 0.0778

d. P(?c < Z < c) = 0.9774

4.4

2. The mean TOEFL score of international

students at a certain university is normally

distributed with a mean of 490 and a standard

deviation of 80. Suppose groups of 30 students

are studied. Find the mean and the standard

deviation for the distribution of sample means.