Question

QUESTION 6 OF 17 A Lyft driver has received 160 reviews with an average rating of 4.4 out of 5 stars. If the driver wanted to raise his average star rating to 4.7, how many consecutive 5-star reviews does he need?

Answer 1

He needs 160 5-star reviews in a role. We can write a function to solve this problem. His current total stars is 4.4*160=704. Suppose he needs x more 5-star reviews, then his total stars will be 704+5x. 160+x is the new number of reviews, and the new average will be 4.7, so 4.7*(160+x)=704+5x. The solution is 160. Besides, if you want to get the answer really fast, you can see that 4.7 is right in the middle of 4.4 and 5, so you can immediately guess that the number of new 5-star reviews should be equal to the number of current reviews.