Problem of the week

Problem:

Manny Kerr runs a company that specializes in grooming and caring for lawns. Manny has a push mower and a powerful riding mower. At one location it takes him 5 hours to cut the entire lawn with the push mower but only 70 minutes with the powerful riding mower.

After 90% of the lawn was cut using the powerful riding mower, the remainder was cut using the push mower.

How many minutes did it take Manny to cut the entire lawn?

Solution:

Step 1:

What I know:

-I know that Manny has a push mower and a powerful riding mower

-At 1 location it takes; 5 hours for push mower, 70 mins for riding mower

-90% of lawn was cut using powerful riding mower

-Rest was cut using push mower

What I want to know:

How many minutes did it take Manny to cut the entire lawn?

Step 2:

Plan:

First we have to find 90% of 70 mins for the powerful riding mower. In order to do that we have to convert the percent into a decimal and multiply it. If I divide the decimal, I will get a higher number, so multiplying it would make the number lower. After I find that, since we used 90%, the remaining percentage would be 10%. So I would convert 10% into a decimal and then find 10% out of 5 hours. For this to be easier to calculate we have to convert the hours into minutes so I would multiply how ever minutes there are in a hour by 10% to find that answer. Once that is finished, I will add both answers together to reach the total time it takes to mow the lawn.

Step 3:

Carry out the plan:

90% of 70

90%=90/100=9/10=0.9

0.9x70=63

63 is 90% of 70

5 hours=how many minutes?

1 hour=60 mins

So 5 hours=5x60

5x60=300

There are 300 mins in 5 hours.

10% of 300

10%=10/100=1/10=0.1

0.1x300=30

30 is 10% of 300

Now let’s add them all up.

30+63=93

It took Manny 93 minutes to mow the entire lawn.

Step 4:

Recheck

93-30=63 OR 93-30=63

300/30=0.1 OR 0.1/30=300

300 mins=how many hours

300/60 (Since there are 60 mins in one hour)=5

5 hours=300 mins

70/63=0.9 OR 0.9/63=70

0.9=9/10=90/100=90%

0.1=1/10=10/100=10%

10% is the remainder out 100% from 90%.

Step 5:

Conclusion

In conclusion, it takes Manny Kerr 63 minutes to mow 90% of the lawn with the Power Riding Mower and 10% of the lawn with the Push Mower.