Martha invited 4 friends to go with her to the movies. there are 120 different ways in which they can sit together in a row of 5 seats, one person per seat. in how many of those ways is martha sitting in the middle seat?

24 ways.

Explanation:

We have been given that Martha invited 4 friends to go with her to the movies. This means that there are 5 persons in total.

We need to find the number of ways in which Martha can sit in the middle seat, so we will fix middle seat for Martha.

Since we have been given that they can sit together in a row of 5 seats, one person per seat, so after giving Martha the middle seat, there are 4 seats left.

Now, we have to find the number of ways t arrange Martha's 4 friends that would be:

Therefore, Martha can sit in the middle seat in 24 ways out of 120 different ways.

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer