Answer:
Option A
Their estimate time is longer than time it will actually take.
Step-by-step explanation:
Given that,
number of hours Sandra takes to mow lawn = 45 minutes
= 0.75 hours
number of hours Kelly takes to mow lawn = 1 hour 15 minutes
= 1.25 hours
Estimate time to mow lawn if both works together = 1 hour
One part of work, if they work together = 1/0.75 + 1/1.25
1.25 + 0.75 /(1.25)(0.75)
2 / (1.25)(0.75)
(for complete work take reciprocal)
Number of hours it take to mow lawn if both work together
(1.25)(0.75) / 2
0.47 hours < 1
