Quantitative Aptitude - Arithmetic Ability Questions

Given a secret is told to 3 persons in 3 minutes.
And if the process continues with each person saying 3 other persons,
In 30 minutes => the rocess for 10 times because each person time is 3 minutes.
Required number of persons = 3 + 32 + 33 + .... + 39 + 310

Now it forms a geometric progression,

Sum to n terms is S = arn - 1r - 1

Here a = 3, r = 3

 
=> 59048 x 3 /2

= 88572.

1. How to find Speed(s) if distance(d) & time(t) is given:

 Speed (S) = Distance (D)Time (T) 

Ex: Find speed if a person travels 4 kms in 2 hrs?

Speed = D/T = 4/2 = 2 kmph.

2.  Similarly, we can find distance (d)  if speed (s) & time (t) is given by

Distance (D) = Speed (S) x Time (T)

Ex : Find distance if a person with a speed of 2 kmph in 2 hrs?

Distance D = S X T = 2 x 2 = 4 kms. 

3.  Similarly, we can find time (t) if speed (s) &  distance (d) is given by

Time (T) = Distance (D)Speed (S)

Ex : Find in what time a person travels 4 kms with a speed of 2 kmph?

Time T = D/S = 4/2 = 2 hrs.

4. How to convert  km/hr into m/sec :

P km/hr = P x 518 m/sec

Ex : Convert 36 kmph into m/sec?

36 kmph = 36 x 5/18 = 10 m/sec 

5. How to convert  m/sec into km/hr :

P m/sec = P x 185 kmph.

Ex : Convert 10 m/sec into km/hr?

10 m/sec = 10 x 18/5 = 36 kmph.

6.  If the ratio of the speeds of A and B is a:b, then the ratio of the times taken by them to cover the same distance is b : a.

7.  Suppose a man covers a certain distance at x km/ hr and an equal distance at y km/hr . Then, the average speed during the whole journey is 2xyx+y km/hr.

From the given data,

P = 140

But it is given that,

40% of Q + Q = 140 = P

=> Q + [40Q/100] = 140

=> [100Q + 40Q]/100 = 140

=> 140Q = 140 x 100

=> Q = 100

Now,

 3/25 of Q 

= (3/25) x 100

= 3 x 4 

= 12 

Required 3/25 of Q  = 12.

Almond Selling price = CP(1 + P%/100)

=> CP = 20000, SP = 23000

=> 23000 = 20000 (1 + P/100)

=> P% = 100(23000/20000 - 1) = 15

Then, Olive's P% = 30%

SP for Olive = CP for Sarah = 23000(1 + 30/100) = 29900

Now Sarah wants to earn profit of 8%

=> Sp for Sarah = 29900(1 + 8/100)

= Rs. 32,292.

v1v2=r12×h1r22×h2 

d1 = 2r1 and d2 = 2r2 are diameters

When a hand of cards is dealt, the order of the cards does not matter. If you are dealt two kings, it does not matter if the two kings came with the first two cards or the last two cards. Thus cards are combinations. There are 52 cards in a deck and we want to know how many different ways we can put them in groups of five at a time when order does not matter. The combination formula is used.

C(52,5) = 2,598,960

We know that, Total probability = 1

Given probability of black stones = 1/4

=> Probability of blue and white stones = 1 - 1/4 = 3/4

But, given blue + white stones =  9 + 6 = 15

Hence,

3/4 ----- 15

 1   -----  ?

=> 15 x 4/3 = 20.

Hence, total number of stones in the box = 20.