Time and Work

1. Worker A takes 8 hours to do a job. Worker B takes 10 hours to do the same Job.How long should it take both A and B, working together but independently, to do the same job? (IGNOU, 2003)
A’s 1 hour's work = 1/8
B's 1 hour's work = 1/10
(A + B)'s 1 hour's work = (1/8) +(1/10)=9/40
Both A and B will finish the work in 40/9 days.

2. A and B together can complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how many days can B alone complete that work?
(Bank P.O.2003)
Sol. (A + B)'s 1 day's work = (1/4).
A's 1 day's work = (1/12).
B's 1 day's work =((1/4)-(1/12))=(1/6)
Hence, B alone can complete the work in 6 days.

3. A can do a piece of work in 7 days of 9 hours each and B can do it in 6 days of 7 bours each. How long will they take to do it, working together 8 hours a day?
A can complete the work in (7 x 9) = 63 hours.
B can complete the work in (6 x 7) = 42 hours.
(A + B)'s 1 hour's work =(1/63)+(1/42)=(5/126)
A’s 1 hour's work = (1/63) and B's 1 hour's work =(1/42)
Both will finish the work in (126/5) hrs.
Number of days. of (42/5) hrs each =(126 x 5)/(5 x 42)= 3 days

ans

IB ACIO Previous Year Question Paper [2012][Current affairs and GK]

Head quarters of WTO is at ?
Geneva, Switzerland

Number of zodiac constellations in Indian astrology ?
27

Ramakrishna Mission is founded by ?
Swami Vivekananda

Curiosity was landed on which location in MARS?
Gale crater

India's pilot less aircraft ?
Lakshya

India's first indigenous nuclear submarine ?
Arihant

First Monday of October is celebrated as ?
World habitat day

Which countries lower parliament is known as Wolesi jirga ?
Afghanistan

What is the present permissible Power Density value for mobile towers operating at 1800 MHz?
9 Watt/ meter²

Centre for Cellular and Molecular Biology or CCMB is an Indian Biotechnology research establishment of the Council of Scientific and Industrial Research located in ?
Hyderabad, India

What is Wakhan Corridor ?
An area of far north-eastern Afghanistan

What does NSAB stand for indian contest ?
National Security Advisory Board

What is the significance of ozone layer in atmosphere ?
Filters ultra violet from sun 
The headquarters of nestle is located at ? 
Vevey, Switzerland 

Which family owns the hero group of companies ? 
Munjals 

Titicaca,the highest lake in the world located at ? 
On the border of Peru and Bolivia 

At which point of earth there is no gravity ? 
At its Centre 

The chemical component of Vinegar is 
Acetic acid 

The gas released from paddy fields 
Methane 

The great victoria desert is located at 
Australia

IB ACIO Previous Year Question Papers[2012][image]