Question

6. A pediatrician claims that the standard deviation of the
heights of 2-year-old boys is less than 1.43 inches. A random
sample of 11 2-year-old boys revealed that their standard deviation
is 1.42 inches. Test the pediatrician’s claim at the 1% level of
significance.

Answer #1

The heights of 11-year old boys in the United States are
normally distributed. A random sample of 9 boys
was taken and their mean height (in inches) was 56.67 and their
sample standard deviation was 3 inches. Perform a
hypothesis test at the 10% significance level to determine if the
mean height of 11-year old boys is more than 54
inches. Give the hypotheses, test statistic, rejection
region, P-value, decision, and interpretation.

2.
A doctor believes that less than 80% of 2-year-old boys are taller
than 33 inches. A random sample of 300 2-year-old boys revealed
that 250 of them are taller than 33 inches. Test the doctor’s
belief at the 5% level of significance.

A doctor believes that more than 80% of 2-year-old boys are
taller than 33 inches. A random sample of 300 2-year-old boys
revealed that 250 of them are taller than 33 inches. Test the
doctor’s belief at the 5% level of significance.

In the United States, the populations mean height for 4-year-old
boys is 39 inches. A researcher believes that non-U.S. 4-year-old
boys are shorter than U.S. 4- year-old boys. Suppose a random
sample of 32 non-U.S. 4-year-old boys showed a sample mean of 38.2
inches with a standard deviation of 3.1 inches. The boys were
independently sampled. Assume that heights are Normally distributed
in the population. Determine whether the population mean for
non-U.S. boys is significantly shorter than the U.S. population...

The heights of European 13-year-old boys can be approximated by
a normal model with mean μ of 63.1 inches and standard deviation σ
of 2.32 inches.
A random sample of 9 European 13-year-old boys is selected. What
is the probability that the sample mean height x is greater than
65.7 inches? (use 4 decimal places in your answer)

According to the children's growth chart the heights of
two-year-old boys are normally distributed with a mean of 32.3
inches and a standard deviation of 1.4 inches. If a two-year-old
boy is selected at random, what is the probability that he will be
more than 34.2 inches tall?

A teacher claims 9 year old girls are taller than 9 year old
boys. Test this claim at an alpha level of .05. A researcher
randomly selected a smaple of 60 boys and sample of 50
girls.
Boys: n=60 mean = 123.5 cm standard deviation = 9.9 cm
Girls: n=50 mean = 126.2 cm standard deviation = 10.9 cm
Use either one sample t or z test. Label critical value and test
value. State p value and show all five...

1. In the united states the population mean height for 4 year
old boys is 39 inches, Suppose a random sample of 32 NON
-US 4 year old boys showed a sample mean of 38.2 inches
with a standard deviation of 3.1inches. The boys were independently
sampled. Assume the heights are normally distributed in the
population. Determine weather the population mean for non us boys
is significantly different from the US population mean, use a
significance level of 5%

In Country A, the population mean height for 3-year-old boys
is 37 inches. Suppose a random sample of 15 3-year-old boys from
Country B showed a sample mean of 36.8 inches with a standard
deviation of 4 inches. The boys were independently sampled. Assume
that heights are Normally distributed in the population. Complete
parts a through c below. a. Determine whether the population mean
for Country B boys is significantly different from the Country A
mean. Use a significance level...

the
mean weight for 6 year old american boys is about 50 with a
standard deviation of 8 pounds. for 13 year old boys mean is about
95 pounds with a standard deviation of 15 pounds. assume the
weights are distributed nornally for thjs problem. what is the
probability that two random 6 year old boys will together weigh
more than a random thirteen year ild boy?

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