Danielle’s chemistry professor has a complicated grading system. Each lab counts once and each test counts as two labs. At the end of the semes-ter there is a fnal lab that counts as three regular labs. Danielle received scores of 84, 81, and 93 on her labs and scores of 89 and 94 on her tests. What score must she get on the fnal lab to receive an A (an A is 90)

92

Step-by-step explanation:

Lab Scores are 84, 81, and 93

Test Scores are 89 and 94

Each lab counts once and each test counts as two labs. At the end of the semester there is a final lab that counts as three regular labs.

Total Number of Labs= (3X1)+(2X2)+(1X3) =3+4+3 =10

To recieve an A(90), the average of her scores must be 90.

Let her final lab score =b

Refer to the attached diagram

Total Score=624+3b

For her average =90

Cross multiplying

624+3b =90 X 10

624+3b =900

3b =900-624

3b =276

Dividing both sides by 3

b= 92

She must score 92 in her final lab to receive an A.