The lengths of human pregnancies can be described by a Normal model with a mean of 268 days and a standard deviation of 15 days.What percentage can we expect for a pregnancy that will last at least 300 days?
A)98.34%
B)1.66%
C)1.79%
D)48.34%
E)1.99%

Question

Quizplus · Accepted Answer

We need to find the percentage of pregnancies lasting at least 300 days. To do this, we need to find the area under the Normal curve to the right of 300 days. We can convert this to a standard Normal distribution by using the formula z = (x - μ) / σ, with x = 300, μ = 268, and σ = 15. This gives us z = 2.1333. Using a Normal distribution table or calculator, we can find that the area to the right of z = 2.1333 is 0.0166 or 1.66%. Therefore, we can expect that only 1.66% of pregnancies will last at least 300 days.

The Lengths of Human Pregnancies Can Be Described by a Normal