Chapter 9: Q.56 (page 540)
A bathroom scale claims to be able to identify correctly any weight within a pound. You think that it cannot be that
accurate. What type of test would you use?
Short Answer
We would use a two-tailed test.
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Chapter 9: Q.56 (page 540)
A bathroom scale claims to be able to identify correctly any weight within a pound. You think that it cannot be that
accurate. What type of test would you use?
We would use a two-tailed test.
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Previously, an organization reported that teenagers spent 4.5 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 4.75 hours with a sample standard deviation of 2.0. Conduct a hypothesis test. At a significance level of a = 0.05, what is the correct conclusion?
a. There is enough evidence to conclude that the mean number of hours is more than 4.75
b. There is enough evidence to conclude that the mean number of hours is more than 4.5
c. There is not enough evidence to conclude that the mean number of hours is more than 4.5
d. There is not enough evidence to conclude that the mean number of hours is more than 4.75
Driver error can be listed as the cause of approximately of all fatal auto accidents, according to the American Automobile Association. Thirty randomly selected fatal accidents are examined, and it is determined that were caused by driver error. Using is the AAA proportion accurate?
La Leche League International reports that the mean age of weaning a child from breastfeeding is age four to five worldwide. In America, most nursing mothers wean their children much earlier. Suppose a random survey is conducted of 21 U.S. mothers who recently weaned their children. The mean weaning age was nine months (3/4 year) with a standard deviation of 4 months. Conduct a hypothesis test to determine if the mean weaning age in the U.S. is less than four years old.
"Japanese Girls鈥 Names"
by Kumi Furuichi
It used to be very typical for Japanese girls鈥 names to end with 鈥渒o.鈥 (The trend might have started around my grandmothers鈥 generation and its peak might have been around my mother鈥檚 generation.) 鈥淜o鈥 means 鈥渃hild鈥 in Chinese characters. Parents would name their daughters with 鈥渒o鈥 attaching to other Chinese characters which have meanings that they want their daughters to become, such as Sachiko鈥攈appy child, Yoshiko鈥攁 good child, Yasuko鈥攁 healthy child, and so on. However, I noticed recently that only two out of nine of my Japanese girlfriends at this school have names which end with 鈥渒o.鈥 More and more, parents seem to have become creative, modernized, and, sometimes, westernized in naming their children.
I have a feeling that, while percent or more of my mother鈥檚 generation would have names with 鈥渒o鈥 at the end, the proportion has dropped among my peers. I wrote down all my Japanese friends鈥, ex-classmates鈥, co-workers, and acquaintances鈥 names that I could remember. Following are the names. (Some are repeats.) Test to see if the proportion has dropped for this generation.
Ai, Akemi, Akiko, Ayumi, Chiaki, Chie, Eiko, Eri, Eriko, Fumiko, Harumi, Hitomi, Hiroko, Hiroko, Hidemi, Hisako, Hinako, Izumi, Izumi, Junko, Junko, Kana, Kanako, Kanayo, Kayo, Kayoko, Kazumi, Keiko, Keiko, Kei, Kumi, Kumiko, Kyoko, Kyoko, Madoka, Maho, Mai, Maiko, Maki, Miki, Miki, Mikiko, Mina, Minako, Miyako, Momoko, Nana, Naoko, Naoko, Naoko, Noriko, Rieko, Rika, Rika, Rumiko, Rei, Reiko, Reiko, Sachiko, Sachiko, Sachiyo, Saki, Sayaka, Sayoko, Sayuri, Seiko, Shiho, Shizuka, Sumiko, Takako, Takako, Tomoe, Tomoe, Tomoko, Touko, Yasuko, Yasuko, Yasuyo, Yoko, Yoko, Yoko, Yoshiko, Yoshiko, Yoshiko, Yuka, Yuki, Yuki, Yukiko, Yuko, Yuko.
The cost of a daily newspaper varies from city to city. However, the variation among prices remains steady with a
standard deviation of 20垄. A study was done to test the claim that the mean cost of a daily newspaper is $1.00. Twelve costs
yield a mean cost of 95垄 with a standard deviation of 18垄. Do the data support the claim at the 1% level?
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