Quantitative Aptitude - Arithmetic Ability Questions

Let the number  be 476ab0 

476ab0 is divisible by 3 

=> 4 + 7 + 6 + a + b + 0 is divisible by 3

=> 17 + a + b is divisible by 3 ------------------------(i)

476ab0 is divisible by 11

[(4 + 6 + b) -(7 + a + 0)] is 0 or divisible by 11

=> [3 + (b - a)] is 0 or divisible by 11  --------------(ii)

Substitute the values of a and b with the values given in the choices and select the values which satisfies both Equation 1 and Equation 2.

if a=6 and b=2, 

17 + a + b = 17 + 6 + 2 = 25 which is not divisible by 3 --- Does not meet equation(i).Hence this is not the answer

if a=8 and b=2, 

17 + a + b = 17 + 8 + 2 = 27 which is divisible by 3 --- Meet equation(i)

[3 + (b - a)] = [3 + (2 - 8)] = -3 which is neither 0 nor divisible by 11---Does not meet equation(ii).Hence this is not the answer

if a=6 and b=5, 

17 + a + b = 17 + 6 + 5 = 28 which is not divisible by 3 --- Does not meet equation (i) .Hence this is not the answer

if a=8 and b=5, 

17 + a + b = 17 + 8 + 5 = 30 which is divisible by 3 --- Meet equation 1

[3 + (b - a)] = [3 + (5 - 8)] = 0 ---Meet equation 2

Since these values satisfies both equation 1 and equation 2, this is the answer

Angle traced by hour hand in214 21 hrs = 36012×2140 =157102 

Angle traced by min. hand in 15 min = 36012×150 = 900 

 Required Angle = 157120-900 = 67102

Recall it is based on inverse proportion or product constancy concept.

     Reducion in price                      increase in amount

         25%     1/4                              1/3   33.33% = 4 oranges

It means original number of oranges = 4 x 3 = 12

original price of oranges = 16/12 = Rs. 1.33

Let the normal speed be x km/h, then 

80x-80(x+4)=1

⇒x2+4x-320=0

⇒x (x + 20) - 16 (x + 20) = 0

(x + 20 ) (x - 16) =0

x = 16 km/h

 Therefore (x + 4) = 20 km/h

 Therefore increased speed = 20 km/h