Question 1050445: The lengths of a particular animal's pregnancies are approximately normally distributed, with mean = 278 days and standard deviation = 16 days.
(a) What proportion of pregnancies lasts more than 290 days?
(b) What proportion of pregnancies lasts between 274 and 286 days?
(c) What is the probability that a randomly selected pregnancy lasts no more than 258 days?
(d) A "very preterm" baby is one whose gestation period is less than 238 days. Are very preterm babies unusual?
How can I solve this (preferably) using a TI calculator?
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website! mean = 278 days and standard deviation = 16 days.
a) P(>290)
TI syntax is normalcdf(smaller, larger, µ, σ).
P(>290) = normalcdf(290, 9999, 278, 16) Note: Placeholder 9999
b)P(274 ≤ x ≤ 286)= normalcdf(274, 286, 278, 16)
c) P(x ≤ 258) = normalcdf(-9999, 258, 278, 16)
d) P(x < 238) = normalcdf(-9999, 238, 278, 16)
Since this is a continuous function, we have P(x < 238) = P(x ≤ 238).
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