Quantitative Aptitude - Arithmetic Ability Questions

Four tenths = 0.4

Five thousandths = 0.005

The average is (0.4 + 0.005)/2 = 0.2025

C.I.= Rs.[4000*(1+10/100)^2-4000]

 =Rs.840

sum=Rs.(420 * 100)/3*8=Rs.1750

Let the present age of person be   x years.

Then, 3(x + 3) - 3(x - 3 ) = x   <=> (3x + 9) - (3x - 9) = x  <=> x = 18..

let the inner and outer radii be r and R meters
then, 2πr = 352/7

=> r = (352/7) * (7/22) * (1/2) = 8m
2πR = 528/7

=> R= (528/7) * (7/22) * (1/2)= 12m
width of the ring = R-r = 12-8 = 4m

Given there are 9 flavours of ice creams.

Each child takes the combination of two flavours and no two children will have the same combination

This can be done by  ways i.e children.

Number of children=C29  = 9 x 8 / 1x 2 = 36.

Let their edges be a and b. Then,

a3/b3 = 1/27 (or) (a/b)3 = (1/3)3 (or) (a/b) = (1/3).

\Ratio of their surface area = 6a2/6b2 = a2/b2 = (a/b)2 = 1/9, i.e. 1:9.

Let ABC be the isosceles triangle and AD be the altitude 

Let AB = AC = x. Then, BC = (32 - 2x). 

Since, in an isosceles triangle, the altitude bisects the base,
so BD = DC = (16 - x).
In triangle ADC,AC2=AD2+DC2 

⇒x2=82+16-x2⇒x=10 

BC = (32- 2x) = (32 - 20) cm = 12 cm. 

Hence, required area =  12*BC*AD=12*12*8=48cm2