One fast typist type some matter in 4hrs and another slow typist type the same matter in 7hrs. If both do combine in how much time they will take to finish.
Choose the correct answer
A) 1 hr 10 mins
B) 1 hr 30 mins
C) 2 hr 32 mins
D) 3 hr 15 mins
E) 4 hr 20 mins
Fast's 1 hr work = 1/4   slow's 1 hr work = 1/7   1/4 + 1/7 = 11/28   they ll finish in 28/11hrs= 2 6/11 ==&gt; 2 hr 32 mins   ANSWER:2 hr 32 mins
<result>C</result>
One fast typist type some matter in 4hrs and another slow typist type the same matter in 7hrs. If both do combine in how much time they will take to finish.