Question

Matt wants to shave 2 1/2 minutes off his 5K race time. After a month of hard training, he managed to lower his overall time from 21 1/5 minutes to 19 1/4 minutes. By how many more minutes does Matt need to lower his race time?

PS: Solve the problem using the RDW strategy. Show all of your work.

Answer 1

Answer:

The answer is 11/20 minutes.

Step-by-step explanation:

First, you have this information:

• Matt wants to shave 2 1/2 mins.
• Before training: overall time 21 1/5 mins.
• After training: overall time 19 1/4 mins.

Now, you have to do the difference between 21 1/5 and 19 1/4, to know how much time Matt shaved.

You have to convert the mixed fractions to a improper fraction.

$21 \frac{1}{5} = \frac{21*5 + 1 }{5} = \frac{105 + 1}{5} = \frac{106}{5}$

$19 \frac{1}{4} = \frac{19*4 + 1 }{4} = \frac{76 + 1}{4} = \frac{77}{4}$

And substract:

$\frac{106}{5} - \frac{77}{4}$

The common denominator for the function 5*4 = 20

$\frac{106}{5} - \frac{77}{4} = \frac{106*4 - 77*5}{20} = \frac{428-385}{20}= \frac{39}{20} = 1 \frac{19}{20}$

Matt shaved 1 19/20 mins.

Now you have to calculate substract 1 19/20 to 2 1/2 to know how many more minutes needs Matt lower his time race.

$2 \frac{1}{2} - \frac{39}{20} = \frac{5}{2} - \frac{39}{20} = \frac{50}{20}-\frac{39}{20} = \frac{11}{20}$