The lengths of pregnancies are normally distributed with a mean of 250 days and a standard deviation of 15 days.

a. Find the probability of a pregnancy lasting 308 days or longer?

b. If we stipulate that a baby is premature if the length of the pregnancy is in the lowest 8% (8th percentile), find the length that separates premature babies from those who are not premature.

a) 0.005% probability of a pregnancy lasting 308 days or longer

b) The pregnancy length that separates premature babies from those who are not premature is 229 days.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean and standard deviation , the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question, we have that:

a. Find the probability of a pregnancy lasting 308 days or longer?

This is 1 subtracted by the pvalue of Z when X = 308. So

has a pvalue of 0.99995

1 - 0.99995 - 0.00005

0.005% probability of a pregnancy lasting 308 days or longer

b. If we stipulate that a baby is premature if the length of the pregnancy is in the lowest 8% (8th percentile), find the length that separates premature babies from those who are not premature.

The 8th percentile is X when Z has a pvalue of 0.08. So it is X when Z = -1.405.

The pregnancy length that separates premature babies from those who are not premature is 229 days.

this is not an educational question, do not offer numerous points just for your own entertainment

intensity of the vector is v= √37 ≈ 6.08 units and make angle ∡α ≈ 9.46° with east direction

step-by-step explanation:

required vector is consists of the two componentsvx= 2+4=6 units   and vy= 1 unit and vx ⊥ vywe will use pythagorian theorem to find intensity of the vector vv∧2 = vx∧2 + vy∧2 => v = √vx∧2 + vy∧2 = √6∧2 + 1∧2 = √36+1 = √37 ≈ 6.08 unitsthe angle ∡α between vector and east direction we wil find with tanαtanα = 1/6 => α = arc tanα = arc 1/6 => α ≈ 9.46°

hope this