(a) There was terrible traffic on the highway, and Kiran drove to work at 15 miles per hour. How

fast would he need to drive home for the average speed for his round trip commute to be 35

miles per hour?

(b) Seetha drove to work at 30 miles per hour. How fast would she need to drive home for the

average speed for her round trip commute to be 40 miles per hour?

Guest Oct 24, 2022

#2**0 **

(a) Let his average speed driving home=S

When the distance back and forth is the same, then:

Average speed =Harmonic mean

[2 x S x 15] / [S + 15] =35, solve for S

**S = - 105 mph ??! - Not possible. You average speed must be less than 30 mph. Check your numbers carefully.**

**(b) [2*30*S] / [30 + S] ==40, solve for S**

**S ==60 mph**

Guest Oct 24, 2022