Welcome to Test-paper.info
Tuesday, January 16 2018 @ 03:16 PM CST
 Select a Forum » General Chat » Primary 1 Matters » Primary 2 Matters » Primary 3 Matters » Primary 4 Matters » Primary 5 Matters » Primary 6 Matters » Question, Feedback and Comments » Education Classified
 Forum Index >  Test Paper Related >  Primary 5 Matters rate and proportion question
 | Printable Version
 By: keenlearner (offline)  Friday, November 09 2012 @ 05:40 AM CST (Read 760 times)
keenlearner

Hi, can anyone teach me how to solve this question. Thanks!

It takes 3 cleaners 2/9 hr to clean an office. How long do 5 cleaners take to clean the same office, assuming every cleaner clean at the same rate?

Junior

Registered: 11/08/12
Posts: 22

 By: jo sarah (offline)  Saturday, November 10 2012 @ 07:49 AM CST
jo sarah

It takes 3 cleaners 2/9 hr to clean an office. How long do 5 cleaners take to clean the same office, assuming every cleaner clean at the same rate?

1/3 of the office is cleaned by a cleaner in 2/9 hr
1 whole of the office will be cleaned by a cleaner in 2/9 x 3 = 2/3 hr
So, 1/5 of the office will be cleaned by a cleaner in 2/15 hr

therefore, the 5 cleaners will clean the same office in 2/15 hr
[because each of the 5 cleans 1/5 of it.]

-------------------------------------------
alternatively, if you understand that for the same piece of work (cleaning the same office),
more cleaners will take less time, then,

the time taken will be (3/5) x (2/9) hr = 2/15 hr

Regular Member

Registered: 03/20/12
Posts: 111

 All times are CST. The time is now 03:16 pm.
 Normal Topic Locked Topic Sticky Topic
 New Post Sticky Topic w/ New Post Locked Topic w/ New Post
 View Anonymous Posts Able to Post HTML Allowed Censored Content