Let the distance of the first part of the race be x, and that of the second part, 15 - x, then
x/8 + (15 - x)/20 = 1.125
5x + 2(15 - x) = 40 x 1.125
5x + 30 - 2x = 45
3x = 45 - 30 = 15
x = 15/3 = 5
Therefore, the distance of the first part of the race is 5 miles and the time is 5/8 = 0.625 hours or 37.5 minutes
The distance of the second part of the race is 15 - 5 = 10 miles and the time is 1.125 - 0.625 = 0.5 hours or 30 minutes.
Answer:
The required probability is 0.988.
Step-by-step explanation:
Consider the provided information.
Based on a poll, 67% of Internet users are more careful about personal information when using a public Wi-Fi hotspot.
That means the probability of more careful is 0.67
The probability of not careful is: 1-0.67 = 0.33
We have selected four random Internet users. we need to find the probability that at least one is more careful about personal information.
P(At least one careful) = 1 - P(None of them careful)
P(At least one careful) = 1 - (0.33×0.33×0.33×0.33)
P(At least one careful) = 1 - 0.012
P(At least one careful) = 0.988
Hence, the required probability is 0.988.
The result may be higher because of the convenience bias in retrieving the sample. Because the survey subjects volunteered to respond not random.

8 out of 300 were defective.
80 pairs were defective
Answer:
The value of the test statistic is t=1.12.
Step-by-step explanation:
This is a hypothesis test for the difference between populations means.
The claim is that the mean amount of time required to reach a customer service representative significantly differs between the two hotels.
Then, the null and alternative hypothesis are:

The sample 1, of size n1=20 has a mean of 2.65 and a standard deviation of √2.952=1.72.
The sample 2, of size n2=20 has a mean of 2.01 and a standard deviation of √2.952=1.89.
The difference between sample means is Md=0.64.

The estimated standard error of the difference between means is computed using the formula:

Then, we can calculate the t-statistic as:
