(Solved): 7. The cost of a daily newspaper varies from city to city but the variation of prices remains stead ...

7. The cost of a daily newspaper varies from city to city but the variation of prices remains steady with a standard deviation of 20 cents. A study was done to test the claim that the mean cost of a daily newspaper is less than \( \$ 1.00 \). Twelve costs yield a mean of 95 cents. Do the data support the claim at the \( 1 \% \) level? 8. In the above problem (\#7), what is the \( p \)-value if the significance was \( 5 \% \) ? Would your decision change? 9. According to an article in a news magazine, the natural ratio of girls to boys is 100 : 105. In China, the birth ratio is \( 100: 114 \) (which is \( 46.7 \% \) girls). Suppose you doubt these figures. You conduct a study where you count the number of girls and boys born in 150 randomly chosen recent births. From the 150 babies, 60 are girls and 90 are boys. Based on your study, do you believe that the percent of girls born in China is \( 46.7 \% \) ? Use a five percent level of significance. 10. In the above problem (\#9), what is the \( p \)-value if the significance was \( 1 \% ? \) Would your decision change?