The weekly incomes of trainees at a local company are normally distributed with a mean of $1,100 and a standard deviation of $250. if a trainee is selected at random, what is the probability that he or she earns less than $1,000 a week?
select one:
a. 0.8141
b. 0.1859
c. 0.6554
d. 0.3446

d. 0.3446

Step-by-step explanation:

We need to calculate the z-score for the given weekly income.

We calculate the z-score of $1000 using the formula

From the question, the standard deviation is dollars.

The average weekly income is dollars.

Let us substitute these values into the formula to obtain:

We now read from the standard normal distribution table the area that corresponds to a z-score of -0.4.

From the standard normal distribution table, .

We round to 4 decimal places to obtain: .

Therefore the probability that a trainee earns less than $1,000 a week is .

The correct choice is D.

b. 6

step-by-step explanation:

we are given the table representing an exponential function.

we can see from the table that, as x is increasing, the value of y is increasing in the power of 6.

i.e. the following relation is obtained,

x = 1, y = 6

x = 2, y = 36 =

x = 3, y = 216 =

x = 4, y = 1296 =

x = 5, y = 7776 =

so, the geometric series obtained is .

thus, the common ratio is given by = = 6.

hence, the common ratio is 6.