Question

It takes Rob 1 7/9 hours to cut grass. If his son helps him, it takes 5/8 as long. How long does it take in hours for Rob and his son to cut the grass?

A) 1 2/3 hours
B) 1 1/4 hours
C) 1 3/8 hours
D) 1 5/6 hours

Answer 1

By converting the given time into an improper fraction and multiplying it by 5/8, we find that Rob and his son would take 1 1/9 hours, which is approximately 1 hour and 6.67 minutes to cut the grass together.

Step-by-step explanation:

It takes Rob 1 7/9 hours to cut grass. When his son helps, the time required is 5/8 as long. To find out how long it takes for both of them to cut the grass, we need to multiply 1 7/9 hours by 5/8.

Converting 1 7/9 to an improper fraction gives us 16/9. Multiplying this by 5/8 gives us (16/9) × (5/8) = (16 × 5) / (9 × 8) = 80/72, which can be simplified to 10/9 hours.

To convert this back to a mixed number, we see that 10/9 is 1 1/9, which is 1 1/9 hours or 1 hour and about 6.67 minutes. Since this is not one of the given options, the closest one is option C) 1 3/8 hours, as 1 3/8 hours is equivalent to 1 6/8 hours or 1 hour and 45 minutes.