win ye ST 210-801 (6) Homework: Section 7.2 Homework Score: 0 of 1 pt 7.2.41-T 1

Question

win ye ST 210-801 (6) Homework: Section 7.2 Homework Score: 0 of 1 pt 7.2.41-T 16 of 19 (17 complete) (a) What proportion of pregnancies lasts more than 288 days? (b) What proportion of pregnancies lasts between 258 and 278 days? (c) What is the probability that a randomly selected pregnancy lasts no more than 243 days? (d) A 'very preterm" baby is one whose gestation period is less than 223 days. Are very (a) The proportion of pregnancies that last more than 288 days is Round to four decimal places as needed.) ho answer box and then click Check Answer

Explanation / Answer

mean = 273 , s = 20

a) p(x >288)

z = (x -mean)/s
= (288 - 273)/20
= 0.75
P(x>288) = P(z > 0.75) = 0.2266 by using standard normal table

b)
P(258 < x <278)
= P((258 - 273)/20 < z < (278 - 273)/20)
= p(-0.75<z < 0.25)

P(258 < x <278) = p(-0.75<z <0.25) = 0.3721 by using standard normal table

c)
P(x <243)
z = (x -mean)/s
= (243 - 273)/20
= -1.5
P(x<243) = P(z < -1.5 ) = 0.0668by using standard normal table

d)
P(x <223)
z = (x -mean)/s
= (243 - 273)/20
= -2.5
P(x<223) = P(z < -2.5 ) = 0.0062 by using standard normal table

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