Question

A tennis team has won 15 out of 20 matches they have played this season. How many more will they have to win in a row to raise their winning percentage to 90%

Answer 1

Explanation:

You see, 15/20 = 75%... 75% = 75/100. So, (15 + t)/(20 + t) = 90%... 90% = 90/100. Solve for (t).

(15 + t)/(20 + t) = 90/100

90(20 + t) = 100(15 + t)

1800 + 90t = 1500 + 100t

10t = 300

t = 30 matches

The team would have to win 30 more matches in a row (that's 45 out of 50 matches).