6. The length of life in months of a certain product is
approximately normally distributed with a mean of 92 and a standard
deviation of 17. For each question below, draw a picture indicating
what you know you need to find. (3 points)
a. the manufacturer decides to guarantee the product for five
years. What percentage of items will fail before the warranty
expires?
b. If the manufacturer wanted to replace only 1% of the product
due to failure under...
Suppose that a population is known to be normally distributed
with μ =2,400 and σ=220. If a random sample of size n=88 is
selected, calculate the probability that the sample mean will
exceed 2,500
P(x > 2,500)=
(Round to four decimal places as needed.)
The life in hours of a certain type of lightbulb is normally
distributed with a known standard deviation of 10 hours. A random
sample of 15 lightbulbs has a sample mean life of 1000 hours. What
would the 99% lower-confidence bound L on the mean life be, rounded
to the nearest integer?
The lifetimes of a certain electronic component are known to be
normally distributed with a mean of 1,400 hours and a standard
deviation of 600 hours. For a random sample of 25 components the
probability is 0.6915 that the sample mean lifetime is less than
how many hours?
A)1345
B)1460
C)1804
D)1790
The length of pain relief from the drug Tramadol is known to be
normally distributed. The pharmaceutical company that makes
Tramadol claims that the average pain relief lasts longer than 4
hours. A random sample of 15 patients on Tramadol had a mean of
4.28 hours and a standard deviation of 0.5 hours.
a) State the hypotheses
b) State the rejection region for 훼=0.025
c) Perform a Student’s T-test and state your conclusion.
d) The p-value for this sample will...
The length of zebra pregnancies is normally distributed, with
mean μ = 380 and standard deviation σ = 10. A random sample of 11
random pregnant zebras is chosen. Find P(x⎯⎯⎯x¯ < 375) for n =
11.
Enter your answer as an area under the curve with 4 decimal
places.
Cherry trees in a certain orchard have heights that are normally
distributed with mean = μ 106 inches and standard deviation = σ 17
.
(a) What proportion of trees are more than 109 inches tall?
(b) What proportion of trees are less than 92 inches tall?
(c) What is the probability that a randomly chosen tree is
between 90 and 105 inches tall?
Round the answers to four decimal places.
Question 4. The demand for a new product is estimated to be
normally distributed with μ = 200 and σ = 40. Let x be the number
of units demanded, and find the following probabilities: a. P(180≤
x ≤220) b. P(x ≥ 250) c. P(x ≤ 100) d. P(225≤ x ≤250)
The length of human pregnancies is approximately normally
distributed with mean μ= 266 days and standard deviation σ = 15
days.
(a) What is the probability a randomly selected pregnancy lasts
less than 262 days?
(b) Suppose a random sample of 20 pregnancies is obtained.
Describe the sampling distribution of the sample mean length of
human pregnancies.
(c) What is the probability that a random sample of 20
pregnancies has a mean gestation period of 262 days or less?
(d)...
Suppose a population of scores x is normally distributed with μ
= 16 and σ = 5. Use the standard normal distribution to find the
probability indicated. (Round your answer to four decimal
places.)
Pr(16 ≤ x ≤ 18.6)