Question

Lisa is participating in a 6 day cross country biking challenge. She hiked for 49,57,52,50 and 53 miles on the first 5 days. How many miles does she need to bike on the last day so that her average(mean) is 51 miles per day

Answer 1

Answer:

45 miles

Explanation:

Let x represent the miles Lisa needs to hike on the last day.

Given the miles she biked on the first 5 days as 49,57,52,50 and 53 and her average(mean) per day as 51 miles per day.

We can go ahead and determine x using the mean formula and substituting the given values into the formula as seen below;

$\begin{gathered} Mean=\frac{\text{Sum of the terms}}{\text{Number of terms}} \\ 51=\frac{49+57+52+50+53+x}{6} \\ 51=\frac{261+x}{6} \end{gathered}$

Let's cross-mulitply;

$\begin{gathered} 261+x=51\cdot6 \\ 261+x=306 \\ x=306-261 \\ x=45\text{ miles} \end{gathered}$

We can see from the above that Lisa needs to bike 45 miles on the last day so that her average(mean) is 51 miles per day.