Quantitative Aptitude - Arithmetic Ability Questions

We know that, 

The area of a triangle with two sides given and included angle

A = 1/2 x product of sides x Sin(angle) 

Here the two sides are 8 & 12

Angle = 150

Area = 1/2 x 8 x 12 x sin150

Sin(150) = sin(90+60) = cos(60) = 1/2

A = 48 x 1/2 = 24

Area of the given triangle = 24 sq units.

A day has 24 hrs

=> If 24 hrs - 100

Then 1 hr = ?

100/24 = 4.16%

Given that to find 15 of 80

=> What % of 80 is 15

Let it be 'p'

=> p% of 80 = 15

=> $$\begin{gathered} p x 80100 = 15 \\ ⇒p = 15 x 10080 \\ ⇒p = 150080 = 18.75 \end{gathered}$$

Therefore, 15 is 18.75% of 80 => 18.75% of 80 = 15

Example::

Now, in the similar way we can find 15% of 80 =?

=> 15x80/100 = p

=> p = 4 x 3 = 12

Therefore, 15% of 80 = 12

A=P(1+r)^t

Let the rate of interest be R

(Interest at rate (R+4)%)–(Interest at R%)

= 600(PT(R+4)/100) –(PTR/100)

= 6003PR +12P –3PR = 60000

12P = 60000

P = 5000

Quarter of Kg means 250 gm

Less weight, less price (Direct Proportion)

So,

250 : 200 :: 60 : x => x = 48

So 200 gm will cost 48 paise.

We know, 

S.I = PTR/100 where P = principal amount, T = time, R = rate of interest

Here in the given data,

Interest for two years S.I = 924 - 812 = Rs. 112

Now, Principal amount P = 812 - 112 = Rs. 700 

Now,

R = S.I x 100/PT

R = 112 x 100/700 x 2

R = 11200/1400

R = 8%

Hence, the rate of interest R = 8%.