a) NORMAL: The mean amount spent by a family on food per monthis $500 with a sta
ID: 2950287 • Letter: A
Question
a) NORMAL: The mean amount spent by a family on food per monthis $500 with a standard deviation of $75. Assuming that the foodcosts are normally distributed, what is the probability that afamily spends more than $410 per month?
b)NORMAL: A resort tracks the number of days each guest stays.They've discovered that this variable is normally distributed witha mean of 9 days and a standard deviation of 3. They would expect10% of the guests stay longer than how many days?
c)SAMPLE SIZES: Comcast wants to know the percentage of theircable subscribers who use the internet at home. How large of asample should they survey to determine the proportion who use theinternet within 2% and with 90% confidence?
Explanation / Answer
a) normal distribution P(lower) P(upper) z X mean std.dev .1151 .8849 -1.20 410 500 75 more than $410 per month would be p(upper) which is 88.49% b) normal distribution P(lower) P(upper) z X mean std.dev .9000 .1000 1.28 12.8447 9 3 10% of guests staying longer than how many days is the X valuewhich is 12.8447 rounded to 13 days. c) Can't seem to answer this problem. If you were given a standarddeviation that would help.
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