Answer:
Step-by-step explanation:
Let X be the length of pregnancy.
X is N(268, 15)
a) Prob of pregnancy lasting 307 days or longer
= P(X>307) = 
=0.5-0.4953
=0.0047
b) Lowest 2% is 2nd percentile
Z=-2.55
X score = 268-2.55(15)
= 229.75 days
If length of days >230 days then it is not premature.
3 times 8 is 24 and adding 7 is 31 so 31/1 divided by 19/1
U must flip the 19/1 to 1/19 and make it multiplication sign
31/1 times 1/19 is 31/19 or 1.63157