Answer:
Time taken = 6.2 hours
Step-by-step explanation:
Firstly, we will calculate the rate of each person per hour. Then we combine the rates and afterward divide the number of envelope they could address by the combined rate.
Casey can address 20 envelopes at the rate of 20 per hour.
Casey rate = 20 envelope per hr
Anne can address 44 envelope in 2 hours
Anne rate = 22 envelope per hr
Paula can address 68 envelope in 3 hours
Paula rate = 68/3 envelope per hr
Time it will take them to address 400 envelope can be solved below
Add their rate = 20 + 22 + 68/3 = 42 + 68/3 = (126 + 68)/3 = 194/3
Time = 400 ÷ 194/3 = 400 × 3/194 = 1200/194 = 6.1855670103
Time taken = 6.2 hours
