Answer: The mean number of checks written per day 
Standard deviation
Variance
Step-by-step explanation:
Given : The total number of checks wrote by person in a year = 126
Assume that the year is not a leap year.
Then 1 year = 365 days
Let the random variable x represent the number of checks he wrote in one day.
Then , the mean number of checks wrote by person each days id=s given by :-
Since , the distribution is Poisson distribution , then the variance must equal to the mean value i.e. 
Standard deviation : 
Answer: 36 seconds
Step-by-step explanation:
A: 9, 18, 27, 36
B: 12, 24, 36
The sample which is likely to produce the most valid result is Richard's sample because there was no statistical bias. Statistical bias is the systematic favoritism of certain individuals in the study. Just like what Adriana, Henry and Malik did in conducting their surveys, they choose people who are point of interest and also who are near them. In the way Richard conducted his survey, he used a random sampling technique, this is a method of selecting a sample from a population in such a way that every possible individual can be chosen and he doesn't know who these people are.
In 1 hour, Antoine travels 1.75 mi by dividing 5.25 by 3. So, after lunch, he hiked 4 hours. 1.75 times 2 is 3.5 mi every hour after lunch. So, 3.5 times 4 is 14 mi. + 5.25 is 19.25 mi., or 19 1/4 miles.
