I need some help on this one!

[SkankingHips]

Cindy has scores of 71, 84, 83 and 89 on her biology tests. Use a compound inequality to find the range of scores she can make on her final exam to receive a C in the course. The final exam counts has two tests, and a C is received if the final course average is from 70 to 79.

Thanks to all.

 

[wjm11]

Cindy has scores of 71, 84, 83 and 89 on her biology tests. Use a compound inequality to find the range of scores she can make on her final exam to receive a C in the course. The final exam counts has two tests, and a C is received if the final course average is from 70 to 79.

Here’s a start. Set up an equation that assumes the final average will be 70:

(71 + 84 + 83 + 89 + 2x)/6 = 70

X will be the required test score. Note that I used 2x instead of just x and that I used 6 in the denominator instead of five. Those two things account for the test being double-weighted (counting as two tests).