SOLUTION: On the first 4 tests your average is 84%. If you think you can score 94% on all the remaining tests, how many more tests do you need to bring your average over 90%?

Algebra ->  Average -> SOLUTION: On the first 4 tests your average is 84%. If you think you can score 94% on all the remaining tests, how many more tests do you need to bring your average over 90%?       Log On


   



Question 561203: On the first 4 tests your average is 84%. If you think you can score 94% on all the remaining tests, how many more tests do you need to bring your average over 90%?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = number of tests needed with score of
94% to average over 90%
+%28+4%2A84+%2B+94x+%29+%2F+%28+4+%2B+x+%29+=+90+
+%28+336+%2B+94x+%29+%2F+%28+4+%2B+x+%29+=+90+
+336+%2B+94x+=+90%2A%28+4+%2B+x+%29+
+336+%2B+94x+=+360+%2B+90x+
+4x+=+360+-+336+
+4x+=+24+
+x+=+6+
7 is the number of tests needed with score of
94% to average over 90%
( 6 test gives exactly 90% average )
check answer:
+%28+4%2A84+%2B+94x+%29+%2F+%28+4+%2B+x+%29+=+90+
+%28+4%2A84+%2B+94%2A6+%29+%2F+%28+4+%2B+6+%29+=+90+
+336+%2B+564+=+90%2A10+
+900+=+900+
OK