According to a government study among adults in the 25- to 34-year age group the

Question

According to a government study among adults in the 25- to 34-year age group the mean amount sport pet year on reading and entertainment is $2, 045. Assume that the distribution of the amounts spent follows the normal distribution with a standard deviation of $515 (Round z-score computation to 2 decimal places and your final answer to 2 decimal places.) (a) What percent of the adults spend more than $2 650 per year on reading and entertainment? Percent ___________ % (b) What percent spend between $2, 650 and $3, 250 per year on reading and entertainment? Percent ___________ % (c) What percent spend less than $1, 200 per year on reading and entertainment? Percent ___________ %

Explanation / Answer

1) here z=(X-mean)/std deviation

hence a)P(X>2650)=1-P(Z<1.1748)=1-0.8800=0.1200~12.00%

b)P(2650<X<3250|)=P(1.1748<Z<2.3398)=0.9904-0.8800=0.1104~11.04%

c)P(X<1200)=P(Z<-1.6408)=0.0504~5.04%

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