STATISTICS
posted by SONIA GOVAN on .
ASSUME THE THE MEAN WEIGHT OF CHILDREN AGES 7 IS 50 POUNDS AND A STANDARD DEVIATION OF 10. wHAT IS THE PROBABLITY THAT A RANDOM SELECTED 7 YEAR OLD WILL HAVE A WEIGHT THAT IS LESS THAT 65

You have to find the zscore.
6550 = 15 then divide by 10 which is z = 1.5
You can then use a ztable or a stat calculator to find the probablity less than 65%
Depending on the table, you may want to find the probability of z = 1.5 or greater and then subtract that number from 1 to get the less than. 
For a normal distribution, what is the probability of randomly selecting a z score greater than Z= 2.0