Question

Question 6 (1 point)

Suppose that one-way commute times in a particular city are normally distributed with a mean of 26.75 minutes and a standard deviation of 2.216 minutes. Would it be unusual for a commute time to be below 37 minutes?

Question 6 options:

1)	It is impossible for this value to occur with this distribution of data.

2)	The value is unusual.

3)	The value is not unusual.

4)	We do not have enough information to determine if the value is unusual.

5)	The value is borderline unusual.

Answer 1

A data point can be considered unusual if it is outside of the 3 standard deviation () range from its mean value (u)

i.e. If

data point > u + 3* (upper limit)

or

data point < u - 3* (lower limit)

We have, u = 26.75, = 2.216

Now, 26.75 + 3*2.216 = 33.398 minutes

26.75 - 3*2.216 = 20.102 minutes

Thus, anything outside of range (20.102, 33.398) is unusual

Now, the commute time below 37 minutes doesn't give clarity as 36 minutes will be unusual, 28 minutes is usual and 18 minutes in unusual even though all of them are less than 37.

Thus, the correct answer is

4) We do not have enough information to determine if the value is unusual.