Keith, Anne, Elizabeth, and Marcus are taking a picture. how many different ways can the friends stand in a horizontal line for the picture?
This is just exactly like the problem about Nick.
Also, I think you mean a straight line.
To find out the number of different ways the friends can stand in a horizontal line for the picture, we can use the concept of permutations, which represents the arrangements of objects in a specific order.
Since there are 4 friends (Keith, Anne, Elizabeth, and Marcus), there are 4 positions to fill in the line.
To calculate the number of permutations, we can simply multiply the number of choices for each position. The first position has 4 possible choices (Keith, Anne, Elizabeth, or Marcus), the second position has 3 choices (as one friend has already been placed in the first position), the third position has 2 choices, and the last position has 1 choice.
Therefore, the number of different ways they can stand in a horizontal line for the picture is:
4 (choices for the first position) * 3 (choices for the second position) * 2 (choices for the third position) * 1 (choice for the last position) = 24.
So, there are 24 different ways they can stand in a horizontal line for the picture.