Question

While riding her bike to the ocean and back home 5 times, Kelly timed herself at 46 mins, 63 mins, 56 mins, 56mins, and 55 mins. She had set a goal of averaging 55 minutes for her rides. How many minutes will she need to spend on her 6th ride to attain her goal?

Answer 1

We have to find how many minutes she need to spend on her 6th ride to have an average of 55 minutes.

If we call t to the time she spends on the 6th ride, we can express the average as the sixth part of the sum of the times:

`(46+63+56+56+55+t)/(6)=(276+t)/(6)`

We can equal this result to 55 minutes and find t as:

`\begin{gathered} (276+t)/(6)=55 \\ 276+t=55*6 \\ 276+t=330 \\ t=330-276 \\ t=54 \end{gathered}`

Answer: she needs to spend 54 minutes on the 6th ride for the average to be 55 minutes.