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Chapter 9: Q. 60 (page 540)
Assume the null hypothesis states that the mean is at most . Is this a left-tailed, right-tailed, or two-tailed test?
This is a test with a right-tailed distribution.
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"Phillip’s Wish," by Suzanne Osorio
My nephew likes to play
Chasing the girls makes his day.
He asked his mother
If it is okay
To get his ear pierced.
She said, “No way!”
To poke a hole through your ear,
Is not what I want for you, dear.
He argued his point quite well,
Says even my macho pal, Mel,
Has gotten this done.
It’s all just for fun.
C’mon please, mom, please, what the hell.
Again Phillip complained to his mother,
Saying half his friends (including their brothers)
Are piercing their ears
And they have no fears
He wants to be like the others.
She said, “I think it’s much less.
We must do a hypothesis test.
And if you are right,
I won’t put up a fight.
But, if not, then my case will rest.”
We proceeded to call fifty guys
To see whose prediction would fly.
Nineteen of the fifty
Said piercing was nifty
And earrings they’d occasionally buy.
Then there’s the other thirty-one,
Who said they’d never have this done.
So now this poem’s finished.
Will his hopes be diminished,
Or will my nephew have his fun?
Over the past few decades, public health officials have examined the link between weight concerns and teen girls' smoking. Researchers surveyed a group of randomly selected teen girls living in Massachusetts (between and years old). After four years the girls were surveyed again. Sixty-three said they smoked to stay thin. Is there good evidence that more than thirty percent of the teen girls smoke to stay thin?
After conducting the test, your decision and conclusion are
a. Reject: There is sufficient evidence to conclude that more thanof teen girls smoke to stay thin.
b. Do not reject: There is not sufficient evidence to conclude that less than of teen girls smoke to stay thin.
c. Do not reject : There is not sufficient evidence to conclude that more than of teen girls smoke to stay thin.
d. Reject : There is sufficient evidence to conclude that less than of teen girls smoke to stay thin.
Previously, an organization reported that teenagers spent hours per week, on average, on the phone. The organization thinks that, currently, the mean is higher. Fifteen randomly chosen teenagers were asked how many hours per week they spend on the phone. The sample mean was hours with a sample standard deviation of . Conduct a hypothesis test, the Type I error is:
a. to conclude that the current mean hours per week is higher than , when in fact, it is higher
b. to conclude that the current mean hours per week is higher than , when in fact, it is the same
c. to conclude that the mean hours per week currently is , when in fact, it is higher
d. to conclude that the mean hours per week currently is no higher than , when in fact, it is not higher
Assume the null hypothesis states that the mean is at least . Is this a left-tailed, right-tailed, or two-tailed test?
The Weather Underground reported that the mean amount of summer rainfall for the northeastern US is at least 11.52 inches. Ten cities in the northeast are randomly selected and the mean rainfall amount is calculated to be 7.42 inches with a standard deviation of 1.3 inches. At the α = 0.05 level, can it be concluded that the mean rainfall was below the reported average? What if α = 0.01? Assume the amount of summer rainfall follows a normal distribution.
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