Answer:
There is evidence to suggest that postpartum women do not get enough sleep
Step-by-step explanation:
Given that in a recent survey of 151 postpartum women, the folks at the National Sleep Foundation found that the mean sleep time was 7.8 hours, with a standard deviation of 1.4 hours.

(left tailed test at 5% significance)
Mean difference = -0.20
Std error of sample = 
Test statistic t = mean difference/std error =
= -1.76
df = 150
p value one tailed = 0.0402
Since p < alpha, we reject H0
There is evidence to suggest that postpartum women do not get enough sleep
Answer:
Check the explanation
Step-by-step explanation:
Kindly check the attached image below to see the step by step explanation to the question above.
Answer: We reject the null hypothesis, and we use Normal distribution for the test.
Step-by-step explanation:
Since we have given that
We claim that
Null hypothesis : 
Alternate hypothesis : 
There is 5% level of significance.

So, the test statistic would be

Since alternate hypothesis is left tailed test.
So, p-value = P(z≤-2.31)=0.0401
And the P-value =0.0401 is less than the given level of significance i.e. 5% 0.05.
So, we reject the null hypothesis, and we use Normal distribution for the test.
Answer:
The probability that all three have type B+ blood is 0.001728
Step-by-step explanation:
For each person, there are only two possible outcomes. Either they have type B+ blood, or they do not. The probability of a person having type B+ blood is independent of any other person. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
The probability that a person in the United States has type B+ blood is 12%.
This means that 
Three unrelated people in the United States are selected at random.
This means that 
Find the probability that all three have type B+ blood.
This is P(X = 3).


The probability that all three have type B+ blood is 0.001728