Answer:
1 hour 56 minutes
Step-by-step explanation:
Given :
Time taken by Lucy = 3 hours 15 minutes = 3.25 hours
Time taken by brother = 4 hours 45 minutes = 4.75 hours
Rate = 1 / time taken
Lucy's rate = 1 / 3.25
Brother's rate = 1 / 4.75
Combined rate = Lucy's rate + brother's rate
Combined rate = 1/3.25 + 1/4.75
Combined rate = 0.5182186
Time taken if they work together = 1/ combined rate
= 1 / 0.5182186
= 1.9296 hours
= 1 hour (0.9296 * 60) minutes
= 1 hour 56 minutes (approximately)
