Sawaal
4
Q:

 (3x + 2) (2x - 5) = ax² + kx + n .

What is the value of a - n + k ?

A) 5 B) 8
C) 9 D) 10

Answer:   A) 5



Explanation:

This is a quadratic equation. To find n we multiply the last terms in each bracket together (2 times -5) = -10

To find ‘a’ we multiply the first terms in each bracket together (3x times 2x) = 6x2, So a = 6.

Thus a - n = 16

To find k we multiply the first term in the first bracket by the second term in the second bracket and add the result to the product of the second term in the first bracket and the first term in the second. (-15x + 4x) = -11x. So k = -11

16 - 11 = 5

Subject: Problems on Numbers
Exam Prep: GRE
Related Questions
Q:

54 is to be divided into two parts such that the sum of 10 times the first and 22 times the second is 780. The bigger part is :

A) 24 B) 34
C) 44 D) 54
 
Answer & Explanation Answer: B) 34

Explanation:

Let the two parts be (54 - x) and x.

Then, 10 (54 - x) + 22x = 780

=> 12x = 240  

=>  x = 20.

Bigger part = (54 - x)  = 34.

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17 17782
Q:

If 50 is subtracted from two-third of a number, the result is equal to sum of 40 and one-fourth of that number. What is the number ?

A) 156 B) 179
C) 198 D) 216
 
Answer & Explanation Answer: D) 216

Explanation:

Let the number be x.

 

Then, 2/3x-50 = 1/4x +50

 

=>  5/12x = 90

 

x = (90 x 12) / 5 = 216 

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6 12492
Q:

If 1 is added to the denominator of a traction, the fraction becomes 1/2. If 1 is added to the numerator of the fraction, the fraction becomes 1. The fraction is :

A) 1/3 B) 2/3
C) 4/3 D) 5/3
 
Answer & Explanation Answer: B) 2/3

Explanation:

Let the fraction be x/y. Then, x /(y+1) = 1/2

=> 2x - y = 1  ..........(i)and 

(x + 1) / y = 1  => x - y =  1 .......(ii)

 Solving (i) and (ii), we get :  x  = 2, y = 3. Hence, the required fraction is 2/3..

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4 7253
Q:

In a two-digit number, the digit in the unit's place is more than twice the digit in ten's place by 1. If the digits in the unit's place and the ten's place are interchanged,difference between the newly formed number and the oiginal number is less than the original number by 1. What is the original number ?

A) 35 B) 36
C) 37 D) 39
 
Answer & Explanation Answer: C) 37

Explanation:

Let the ten's digit be x. Then, unit's digit = 2x + 1.

[10x + (2x + 1)] - [{10 (2x + 1) + x} - {10x + (2x + 1)}] = 1

<=> (12x + 1) - (9x + 9) = 1 <=> 3x = 9, x =  3.

So, ten's digit = 3 and unit's digit = 7. Hence, original number = 37.

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55 40278
Q:

A number is doubled and 9 is added. If the resultant is trebled, it becomes 75. What is that number ? 

A) 2 B) 4
C) 6 D) 8
 
Answer & Explanation Answer: D) 8

Explanation:

Let the number be v. Then, 3 (2x + 9) = 75.

 2x + 9 = 25

=> 2x = 16

=> x = 8

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Filed Under: Problems on Numbers

3 10371
Q:

Three numbers are in the ratio 4 : 5 : 6 and their average is 25. The largest number is :

A) 30 B) 40
C) 50 D) 60
 
Answer & Explanation Answer: A) 30

Explanation:

Let the numbers be 4x, 5x and 6x, Then, (4x + 5x + 6x ) / 3 = 25  

=> 5x = 25

=> x = 5. 

Largest number  6x = 30.

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38 27231
Q:

The difference between a number and its three-iflh is 50. What is the number ?

A) 75 B) 100
C) 125 D) 150
 
Answer & Explanation Answer: C) 125

Explanation:

Let the number be x. Then, x - 3x/5 = 50  <=>  x = (50 * 5) / 2 = 125..

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0 3797