Let X be the iq score of adults. X is normally distributed with mean of 100 and standard deviation of 20.
If all iq scores are converted to z -scores then we will get z scores. And the z score is standard normal variable with mean=0 and standard deviation =1
Hence the mean and standard deviation of of all z scores will be 0 and 1 respectively.
Your reasoning and your answer were both correct. Discuss with the teacher. ("Discuss". DON'T fight.)
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Answer: 150 <= x < 250
Step-by-step explanation:
A number, x, rounded to 1 significant figure is 200
Write down the error interval for x
Rounding x to 1 significant figure means that all subsequent digits after the first is rounded down to zero(0) (if the immediate number after the first is digit 5 or more, it is rounded to 1 and added to the first digit).