40.7k views
0 votes
The weight of laboratory grasshoppers follows a Normal distribution, with a mean of 90 grams and a standard deviation of 2 grams. What percentage of the grasshoppers weigh between 86 grams and 94 grams

User JoCuTo
by
8.7k points

1 Answer

0 votes

Answer:

95.44% of the grasshoppers weigh between 86 grams and 94 grams.

Explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean
\mu and standard deviation
\sigma, the z-score of a measure X is given by:


Z = (X - \mu)/(\sigma)

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Mean of 90 grams and a standard deviation of 2 grams.

This means that
\mu = 90, \sigma = 2

What percentage of the grasshoppers weigh between 86 grams and 94 grams?

The proportion is the p-value of Z when X = 94 subtracted by the p-value of Z when X = 86. So

X = 94


Z = (X - \mu)/(\sigma)


Z = (94 - 90)/(2)


Z = 2


Z = 2 has a p-value of 0.9772.

X = 86


Z = (X - \mu)/(\sigma)


Z = (86 - 90)/(2)


Z = -2


Z = -2 has a p-value of 0.0228.

0.9772 - 0.0228 = 0.9544

0.9544*100% = 95.44%

95.44% of the grasshoppers weigh between 86 grams and 94 grams.

User Antonyt
by
8.1k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories