Beth started a workout program. On Monday, she did 15 sit-ups. On Tuesday, she did 21 sit-ups, and on Wednesday, Beth did 27 sit-ups. Make a conjecture about the number of sit-ups Beth will do on Friday.

A.
40

B.
33

C.
45

D.
39

1 answer

To predict the number of sit-ups Beth will do on Friday, let's analyze the given data and identify any pattern.

Beth's sit-ups over the first three days are as follows:
- Monday: 15 sit-ups
- Tuesday: 21 sit-ups
- Wednesday: 27 sit-ups

Next, let's look at the differences between the number of sit-ups done each day:
- From Monday to Tuesday: \( 21 - 15 = 6 \)
- From Tuesday to Wednesday: \( 27 - 21 = 6 \)

This indicates that the number of sit-ups increases by 6 each day. If this pattern continues, we can predict the number of sit-ups for the subsequent days:

- Thursday: \( 27 + 6 = 33 \)
- Friday: \( 33 + 6 = 39 \)

Therefore, based on this pattern, Beth is expected to do 39 sit-ups on Friday.

So the correct answer is:

D. 39