## An index that is a standardized measure used in observing infants over time is approximately normal with a mean of 90 and a standard deviati

Question

An index that is a standardized measure used in observing infants over time is approximately normal with a mean of 90 and a standard deviation of 12. Use StatCrunch to find the proportion of children have an index of at least 110.

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2021-11-23T23:23:35+00:00
2021-11-23T23:23:35+00:00 1 Answer
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## Answers ( )

Answer:The proportion of children that have an index of at least 110 is 0.0478.Step-by-step explanation:The given distribution has a mean of 90 and a standard deviation of 12.

Therefore mean, = 90 and standard deviation, = 12.

It is given to find the proportion of children having an index of at least 110.

We can take the variable to be analysed to be x = 110.

Therefore we have to find p(x < 110), which is left tailed.

Using the formula for z which is p( Z < ) we get p(Z < = 1.67).

So we have to find p(Z ≥ 1.67) = 1 – p(Z < 1.67)

Using the Z – table we can calculate p(Z < 1.67) = 0.9522.

Therefore p(Z ≥ 1.67) = 1 – 0.9522 = 0.0478

Therefore the proportion of children that have an index of at least 110 is 0.0478