posted by Jay on .
Can someone help me verify if this is correct?
Gasoline usage for compact cars in Canada is a normal distribution with a mean of 33.3 km/l and with standard deviation of 7.3 km/L. Round your answers to one decimal place.
a) What percentage of compact cars obtains 20km/L or LESS?
z= x-mean/standard deviation
= 1.82 Km/L
(find percent through z-score table)
which becomes 0.0344 x 100
= 3.4 %
b) What percentage of compact cars obtains MORE than 40 km/L
= 0.92 km/L = 0.8212
= 1 - 0.8212
= 0.1788 x 100
Question is, for question b, is it 1-0.8212 or 100-0.8212?
a) Z = -1.82 ≠ 1.82 Km/L
Otherwise it is correct.
b) Z = .92 (not km/L)
Don't need to subtract from one (which is correct of the two), if you use column for proportion in smaller area in the table.
Final answer correct.