Jacob has a mean score of 78 after his first four math tests. He wants to make a B, or an average

Question

of 80, in math. What does he need to score on the fifth test to have a mean score of 80?

answers:

82

88

94

108

Answer 1

To find out what Jacob needs to score on his fifth test to achieve a mean score of 80, we first need to calculate his total score after the first four tests.

Since the mean of the first four tests is 78, we can find the total score for those tests by multiplying the mean by the number of tests:

\[ \text{Total score after 4 tests} = \text{Mean} \times \text{Number of tests} = 78 \times 4 = 312 \]

Next, let \( x \) be the score Jacob needs on the fifth test. To have an average of 80 after five tests, we need to set up the following equation:

\[ \frac{312 + x}{5} = 80 \]

Now, we need to solve for \( x \):

1. Multiply both sides by 5: \[ 312 + x = 400 \]

2. Subtract 312 from both sides: \[ x = 400 - 312 \] \[ x = 88 \]

Jacob needs to score 88 on his fifth test to achieve a mean score of 80.

So, the answer is 88.