Louise got scores 88 and 78 on her first two tests. What score must she make on her third test to keep an average of 80 or greater?

You want the average of three scores to be at least 80:

(88 + 78 + x)/3 ≥ 80

88 + 78 + x ≥ 80(3)

166 + x ≥ 240

x ≥ 74

You must make at least 74 on the 3rd test to maintain an average of at least 80%

Step-by-step explanation:

she must make a 74 or greater in order for her grade to average out to be 80+

Step-by-step explanation:

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,

part a: 1.08

part b: 27.59