A company produces steel rods. The lengths of the steel rods are normally distributed with a mean of 160-cm and a standard devia

Question

3 years ago

10

A company produces steel rods. The lengths of the steel rods are normally distributed with a mean of 160-cm and a standard devia

tion of 1.2-cm. For shipment, 15 steel rods are bundled together. Find the probability that the average length of a randomly selected bundle of steel rods is less than 159.4-cm. P(M < 159.4-cm) = 0.3085 Enter your answer as a number accurate to 4 decimal places. Answers obtained using exact z-scores or z-scores rounded to 3 decimal places are accepted.

Mathematics

1 answer:

Elden [556K] · Answer 1 · 2022-06-16T04:58:47+03:00

Elden [556K]3 years ago

7 0

Use a z-test where z=(xbar-mean)/sigma/sqrt(n)
The denominator is the SE and is 1.6/sqrt(30)=0.292
z=-0.5/0.292 and .9/.292 or between -1.71 and 3.08
that probability is 0.9553.