Question
Quiz #8 | 3DX 3 (1 complete) The longths of e particular animats pregnancies are appeaximately normally dismibuted, with mean p 256 days and (a) What proportion of pregnancles lasts more than 261 days? )What proportion of pregnancies lasts between 241 and 266 days? What is the probability that a randomly selected pregnancy lasts no more than 25t d) A very preterm baby is one whose gestation period cack the icon to vow a table of areas under the normal curve. (s) The proporion af pregnandies that last move than 261 days is Round to four decimal places es needed) b) The proportion of pregnancies that last between 241 and 266 days is Round to four decimal places as needed) c) The probablity that a randomly selected pregnancy lasts no more than 251 days is Round to four decimal plsces as needed ) di A Vary pretem' baby is one whose gestation peslod is less thian 206 days. Are very preterm babies unusuan The probability of this event is 1-1 so it f 'be unusual because the probabilty is , than 005 Round to tour decimal places as needed mer your arnswer in each of the answer boxes
Explanation / Answer
Formula: z = (x - mean)/std. dev.
a) P(x > 261) = P(Z > (261 - 256)/20) = P(Z > 0.25) = 1 - P(z < 0.25) = 0.4013
b) P(241 < x < 266) = P(Z < 2) - P(Z < -0.75) = 0.9772 - 0.2266 = 0.7506
c) P(X < 251) = P(Z < -0.25) = 0.4013
d) P(X < 206) = P(Z < -2.5) = 0.0062
The probability is less than 0.05, therefore it is unusual
