Question 1073026
Latisha wants a average of 86% in history class.
 Her past scores are 90%, 82%, 81%.
 If this test is double points.
 What percent does she need to get a average of 86%?
:
The reason they divide by 5 is because the last test counts "double" on her average, therefore we treat it like two test
:
let x = the score on the last test
{{{((90 + 82 + 81 + 2x))/5}}} = 86
multiply both sides by 5, add up the scores
253 + 2x = 5(86)
2x = 430 - 253
2x = 177
x = 177/2
x = 88.5 would give her a 86% average