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Refer to the previous problem. Conduct a hypothesis test to see if your decision and conclusion would change if your belief were that the brown trout’s mean I.Q. is not 4.

According to an article in Newsweek , the natural ratio of girls to boys is 100:105. In China, the birth ratio is 100: 114 (46.7% girls). Suppose you don’t believe the reported figures of the percent of girls born in China. You conduct a study. In this study, you count the number of girls and boys born in 150 randomly chosen recent births. There are 60 girls and 90 boys born of the 150. Based on your study, do you believe that the percent of girls born in China is 46.7?

  • -1.64
  • 0.1000
  • Decision: Do not reject null
  • ( 0 . 3216 , 0 . 4784 ) size 12{ \( 0 "." "3216",0 "." "4784" \) } {}

A poll done for Newsweek found that 13% of Americans have seen or sensed the presence of an angel. A contingent doubts that the percent is really that high. It conducts its own survey. Out of 76 Americans surveyed, only 2 had seen or sensed the presence of an angel. As a result of the contingent’s survey, would you agree with the Newsweek poll? In complete sentences, also give three reasons why the two polls might give different results.

The mean work week for engineers in a start-up company is believed to be about 60 hours. A newly hired engineer hopes that it’s shorter. She asks 10 engineering friends in start-ups for the lengths of their mean work weeks. Based on the results that follow, should she count on the mean work week to be shorter than 60 hours?

Data (length of mean work week): 70; 45; 55; 60; 65; 55; 55; 60; 50; 55.

  • t 9 size 12{t rSub { size 8{9} } } {}
  • -1.33
  • 0.1086
  • Decision: Do not reject null
  • ( 51 . 886 , 62 . 114 ) size 12{ \( "51" "." "886","62" "." "114" \) } {}

Use the “Lap time” data for Lap 4 (see Table of Contents) to test the claim that Terri finishes Lap 4, on average, in less than 129 seconds. Use all twenty races given.

Use the “Initial Public Offering” data (see Table of Contents) to test the claim that the mean offer price was $18 per share. Do not use all the data. Use your random number generator to randomly survey 15 prices.

The following questions were written by past students. They are excellent problems!

18. "Asian Family Reunion" by Chau Nguyen

Every two years it comes around We all get together from different towns.In my honest opinion It's not a typical family reunionNot forty, or fifty, or sixty, But how about seventy companions!The kids would play, scream, and shout One minute they're happy, another they'll pout.The teenagers would look, stare, and compare From how they look to what they wear.The men would chat about their business That they make more, but never less.Money is always their subject And there's always talk of more new projects.The women get tired from all of the chats They head to the kitchen to set out the mats.Some would sit and some would stand Eating and talking with plates in their hands.Then come the games and the songs And suddenly, everyone gets along!With all that laughter, it's sad to say That it always ends in the same old way.They hug and kiss and say "good-bye" And then they all begin to cry!I say that 60 percent shed their tears But my mom counted 35 people this year.She said that boys and men will always have their pride, So we won't ever see them cry.I myself don't think she's correct, So could you please try this problem to see if you object?

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Source:  OpenStax, Elementary statistics. OpenStax CNX. Dec 30, 2013 Download for free at http://cnx.org/content/col10966/1.4
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