Tuesday, October 16, 2012

Shortcuts in solving aptitude-7

Allegation or Mixtures

Important Facts and Formulae:

1. Allegation: It is the rule that enables us to find the Ratio in which two of more ingredients at the given price must be mixed to produce a mixture of a desired price.

2. Mean Price: The cost price of a unit quantity of the mixture is called the mean price.

3. Rule of Allegation: If two ingredients are mixed then
Quantity of Cheaper / Quantity of Dearer = (C.P of Dearer – Mean Price) /(Mean Price–C.P of Cheaper).

C.P of a unit quantity of cheaper(c)    C.P of unit quantity of dearer (d)

Mean Price (m)

(d-m)                                               (m-c)

Cheaper quantity: Dearer quantity = (d-m):(m-c)

4. Suppose a container contains x units of liquid from which units are taken out and replaced by water. After n Operatations the quantity of pure liquid = x (1 – y/x)n units.

To exercise some problems on allegation or mixtures visit here

Boats and Streams

Important facts:

1)In water, the direction along the stream is called downstream.

2)Direction against the stream is called upstream.

3)The speed of boat in still water is U km/hr and the speed of
stream is V km/hr then

speed downstream =U + V km/hr
speed up stream = U – V km/hr

Formulae:

If the speed downstream is A km/hr and the speed up stream is
B km/hr then speed in still water = ½(A+B) km/hr
rate of stream =1/2(A-B) km/hr

To exercise some problems on Boats and streams visit here