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Q:

A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

A) 10/21 B) 11/21
C) 1/2 D) 2/7
 
Answer & Explanation Answer: A) 10/21

Explanation:

Total number of balls = (2 + 3 + 2) = 7.

 

Let S be the sample space.

 

Then, n(S) = Number of ways of drawing 2 balls out of 7 =7C2 = 21

 

Let E = Event of drawing 2 balls, none of which is blue.

 

n(E) = Number of ways of drawing 2 balls out of (2 + 3) balls =5C2 = 10

 

Therefore, P(E) = n(E)/n(S) = 10/ 21.

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Filed Under: Probability

Q:

A sum of Rs.1550 was lent partly at 8% p.a. simple interest. The total interest received after 3 years was Rs.300. The ratio of the money lent at 5% to that lent at 8% is :

A) 5:8 B) 6:7
C) 16:15 D) 17:18
 
Answer & Explanation Answer: C) 16:15

Explanation:

let the sum lent at 5% be Rs.x and that lent at 8% be Rs.(1550-x). then, 

 

Interest on x at 5% for 3 years + interest on (1550-x) at 8% for 3 years = 300

 

 x*5*3100+1500-x*8*3100=300 

 

 x=800

 

Required ratio =  x : (1550-x) = 800 : (1550-800) = 800 : 750 = 16 : 15

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Filed Under: Simple Interest
Exam Prep: Bank Exams
Job Role: Bank PO

Q:

In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?

A) 1/3 B) 3/5
C) 8/21 D) 7/21
 
Answer & Explanation Answer: A) 1/3

Explanation:

Total number of balls = (8 + 7 + 6) = 21.

Let E = event that the ball drawn is neither red nor green 

            = event that the ball drawn is blue.

n(E) = 7.

P(E) = n(E)/n(S) = 7/21 = 1/3.

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Filed Under: Probability

Q:

A sum of money becomes 7/6 of itself in 3 years at a certain rate of simple interst. The rate per annum 

A) 5% B) 5.5%
C) 6% D) 6.5%
 
Answer & Explanation Answer: B) 5.5%

Explanation:

sum = x. amount =7x/6.

S.I. =(7x/6 – x) = x/6 ; time = 3 years

Rate =[ (100 * x) / (x * 6 * 3)]% = 5.5%

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Q:

Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

A) 1/2 B) 3/5
C) 9/20 D) 8/15
 
Answer & Explanation Answer: C) 9/20

Explanation:

Here, S = {1, 2, 3, 4, ...., 19, 20}.

Let E = event of getting a multiple of 3 or 5 = {3, 6 , 9, 12, 15, 18, 5, 10, 20}.

P(E) = n(E)/n(S) = 9/20.

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Filed Under: Probability

Q:

If a sum of money at simple interest doubles in 6 years, it will become  4 times in

A) 15years B) 16years
C) 17years D) 18years
 
Answer & Explanation Answer: D) 18years

Explanation:

 

 

 

 

 

 

let sum =x . s.i.=x

 

 

 

rate =(100*x)/(x*6)=50/3%

 

 

 

now ,sum =x, s.i= 3x, rate =50/3%

 

 

 

time =(100*3x)/(x*50/3) = 18 years

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Q:

The true discount on Rs. 2562 due 4 months hence is Rs. 122. The rate percent is?

A) 12% B) 13%
C) 15% D) 14%
 
Answer & Explanation Answer: C) 15%

Explanation:

P.W = 2562-122 =Rs.2440   

Rate = [100 x 122] / [2440 x (1/3)] =15%

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Filed Under: True Discount

Q:

What is the compound interest earned at the end of 3 years?

I. Simple interest earned on that amount at the same rate and for the same period is Rs. 4500.

II.The rate of interest is 10 p.c.p.a.

III.Compound interest for 3 years is more than the simple interest for that period by Rs.465.

A) I and II only B) II and III only
C) I and III only D) Either II or III only
 
Answer & Explanation Answer: D) Either II or III only

Explanation:

 

 

 

 

 

 

I. gives, S.I for 3 years = Rs. 4500.

 

 

 

II. gives, Rate = 10% p.a.

 

 

 

III. gives, (C.I.) - (S.I.) = Rs. 465.

 

 

 

Clearly, using I and III we get C.I. = Rs. (465 + 4500).

 

 

 

Thus, II is redundant.

 

 

 

Also, from I and II, we get sum =

 

 

 

100 x 4500

 

 

 

= 15000.

 

 

 

10 x 3

 

 

 

Now C.I. on Rs. 15000 at 10% p.a. for 3 years may be obtained.

 

 

 

Thus, III is redundant.

 

 

 

Either II or III is redundant.

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