The mean diameter of a ball bearing produced by a certain ...

[ts19998]

The mean diameter of a ball bearing produced by a certain manufacturer is 0.80 cm with a standard deviation of 0.03 cm. A sample of 36 ball bearings is randomly selected from a production run. Use Excel to answer the following questions:
 a. What is the probability that the sample of ball bearings will have a mean less than 0.798 cm?
  b. What is the probability that the sample of ball bearings will have a mean of at least 0.815 cm?
  c. What is the probability that the sample of ball bearings will have a mean between 0.798 and 0.815 cm?
 d. For samples of size 36, 15 of all sample means are at most what diameter?

Question 2

For a standard normal distribution, the probability of z  0 is _____.
 a. 0
  b. .5
  c. .5
  d. 1

[Dinolord]

Answer to Question 1

a. .344578
=NORM.DIST(0.798,0.8,0.005,TRUE)
b. .00135
=1  NORM.DIST(0.815,0.8,0.005,TRUE)
c. .654072
=NORM.DIST(0.815,0.8,0.005,TRUE)
NORM.DIST(0.798,0.8,0.005,TRUE)
d. .794818
=NORM.INV(0.15,0.8,0.005)

Answer to Question 2

c

[ts19998]

TYSM

[duy1981999]

Gracias!