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scastillo924
04-21-2009, 11:52 PM
I finished the rest of my homework but this one question is frustrating me and I can't figure it out. someone help please.

The weekly food cost for a family of 4 is normally distributed with a mean \$158.29 and a standard deviation of \$31.48. What are the low and high weekly food costs for the middle 60% of families from this distribution?

Dragan
04-22-2009, 12:24 AM
I finished the rest of my homework but this one question is frustrating me and I can't figure it out. someone help please.

The weekly food cost for a family of 4 is normally distributed with a mean \$158.29 and a standard deviation of \$31.48. What are the low and high weekly food costs for the middle 60% of families from this distribution?

What are the Z-Scores that capture (or enclose) the middle 60% of the standard normal distribution?

Once you've determined this, then use the linear transformation:

Low =(-Z)*std + mean

High = (Z)*std + mean

scastillo924
04-22-2009, 01:26 AM
got the answer ! thanks !

low= -.84(31.48) + 158.29= 184.73
high= .84(31.48) +158.29=131.84

Dragan
04-22-2009, 02:39 AM
got the answer ! thanks !

low= -.84(31.48) + 158.29= 184.73
high= .84(31.48) +158.29=131.84

Really?...How did you obtain Z-Scores of +-.84?