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a) For this problem, calculate a Z score and use the normal probability Z table or technology to get the probability.
x is 4 hours in minutes, which is 240 minutes
b) To find the quartiles,
Find Z values for the lower 25% and the upper 25% of the data, which is -0.67 and 0.67
The lower quartile(25%) is,
260 + (-0.67)(50) = 226.50
The upper quartile(75%) is,
260 + (0.67)(50) = 293.50
c) To find what value is exceeded with 95% probability, find the Z value for bottom 5%, so look up .0500 on the Z table, which is -1.65
260 + (-1.65)(50) = 177.50
The value exceeded with 95% probability is 177.50