False, 4-2(3+7) = -16 and 4-2•3+2•7= 12
Answer:
68% of pregnancies last between 250 and 282 days
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 266
Standard deviation = 16
What percentage of pregnancies last between 250 and 282 days?
250 = 266 - 16
250 is one standard deviation below the mean
282 = 266 + 16
282 is one standard deviation above the mean
By the Empirical Rule, 68% of pregnancies last between 250 and 282 days
Answer: 0.3439
Step-by-step explanation:
Given :The last four digits for telephone numbers are randomly selected (with replacement).
Here , each position can be occupied with any of the digit independently .
Total digits = 10
Total digits other than 0 = 9
For each digits , the probability that it is not 0 = 
If we select 4 digits , The probability of getting no 0 =
(By multiplication rule of independent events)
Now , the probability that for one such phone number, the last four digits include at least one 0. = 1- P(none of them is 0)
=1- 0.6561=0.3439
Hence, the probability that for one such phone number, the last four digits include at least one 0. is 0.3439 .