Lisa is currently taking physics as one of her electives in school. Her grade at the end of the year is determined by the average of four exams, each worth 100 points. On her first test she got an 84, on her second she got a 92, and on her third an 80. What must she score on her fourth exam to get exactly 80% in the course?

64

Step-by-step explanation:

From the question, we are informed that Lisa is currently taking physics as one of her electives in school and that her grade at the end of the year is determined by the average of four exams, each worth 100 points.

First test = 84,

Second test = 92

Third test = 80

Forth test = y

The fourth test is denoted by y.

Since we are told that she must get exactly 80% in the course and she took 4 exams, that means her total score will be: = 80 × 4 = 320

Therefore,

84 + 92 + 80 + y = 320

256 + y = 320

y = 320 - 256

y = 64

The fourth exam's score is 64

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step-by-step explanation: