Answered

The lengths of a particular​ animal's pregnancies are approximately normally​ distributed, with mean muequals252 days and standard deviation sigmaequals12 days.
​(a) What proportion of pregnancies lasts more than 273 ​days?
​(b) What proportion of pregnancies lasts between 249 and 261 ​days?
​(c) What is the probability that a randomly selected pregnancy lasts no more than 237 ​days?
​(d) A​ "very preterm" baby is one whose gestation period is less than 234 days. Are very preterm babies​ unusual?
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Answer :

Laureneon

Step-by-step explanation:

Normalcdf on a TI-84 is found by pressing 2nd->vars->2

A) normalcdf(low = 273, high = ∞, mu = 252, sd = 12) = .04

B) normalcdf(low = 249, high = 261, mu = 252, sd = 12) = .372

C) normalcdf(low = 0, high = 237, mu = 252, sd = 12) = .106

D) normalcdf(low = 0, high = 234, mu = 252, sd = 12) = .067

    Yes, this is unusual since there is only a 6.7% chance of it occurring.

Hope this helps!

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