Question

th+logical+th Electricity bills: According to a government energy agency, the mean monthly household electricity bill in the United States in 2011 was $109.77. Assume the amounts are normally distributed with standard deviation $22.00. Use the TI-84 Plus calculator to answer the following (a) Find the 8th percentile of the bill amounts. (b) Find the 69th percentile of the bill amounts. (c) Find the median of the bill amounts. Round the answers to at least two decimal places Part 1 of 3 The 8th percentile of the bill amounts is $ Part 2 of 3 The 69th percentile of the bill amounts is $ . Part 3 of 3 The median of the bill amounts is s

Answer 1

(use commnad invnorm( percentile/100,0,1) to get critical value of z)

1)

for 8th percentile critical value of z=		-1.41
therefore corresponding value=mean+z*std deviation=			78.86

2)

for 69th percentile critical value of z=		0.50
therefore corresponding value=mean+z*std deviation=			120.68

3)

for 50th percentile critical value of z=		0.00
therefore corresponding value=mean+z*std deviation=			109.77