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
Q:

A number when subtracted by 1/7 th of itself gives the same value as the sum of all the angles of a triangle. What is the number?

A) 420 B) 210
C) 70 D) 35
 
Answer & Explanation Answer: B) 210

Explanation:

Let the required number be 'p'

We know, sum of angles in a triangle are 180 deg

According to given data,

p - p/7 = 180

7p - p = 180 x 7

=> 6p = 1260

=> p = 1260/6 = 210

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4 2819
Q:

What is the common ratio of the following geometric sequence?

4, 2, 1, 0.5, 0.25, 0.125,...

A) 0.5 B) -1
C) 1.5 D) -0.5
 
Answer & Explanation Answer: A) 0.5

Explanation:

In mathematics, a geometric progression, also known as a geometric sequence, is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed, non-zero number called the common ratio.

 

Herein the given sequence, 4, 2, 1, 0.5, 0.25, 0.125,...

Common Ratio r = 2/4 = 1/2 = 0.5/1 = 0.25/0.5 = 0.125/0.25 == 0.5.

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2 19511
Q:

What is the place value of 6 in 64?

A) 6 B) 60
C) 64 D) 10
 
Answer & Explanation Answer: B) 60

Explanation:

We know that,

● Each digit has a fixed position called its place.

● Each digit has a value depending on its place called the place value of the digit.

● The face value of a digit for any place in the given number is the value of the digit itself

● Place value of a digit = (face value of the digit) × (value of the place).

 

Hence, the place value of 6 in 64 = 6 x 10 = 60.

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226 52063
Q:

Which one of the following is not a prime number?

A) 91 B) 71
C) 41 D) 31
 
Answer & Explanation Answer: A) 91

Explanation:

Prime Numbers :: Numbers which are divisible by only 1 and itself are Prime Numbers.

 

It's answer will be 91.

Because 91 can be divisible by 7,13,91,1.

It is quite clear that prime number should be divisible only by itself and by 1.

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Q:

There are 5 consecutive odd numbers. If the difference between square of the average of first two odd number and the of the average last two odd numbers is 396, what is the smallest odd number?

A) 29 B) 27
C) 31 D) 33
 
Answer & Explanation Answer: A) 29

Explanation:

Let the five consecutive odd numbers be x-4, x-2, x, x+2, x+4

According to the question,

Difference between square of the average of first two odd number and the of the average last

two odd numbers is 396

i.e, x+3 and x-3

x + 32 - x - 32 = 396 x2 + 9 + 6x - x2 + 6x - 9 = 396 12x = 396 x = 33

 

Hence, the smallest odd number is 33 - 4 = 29.

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4 4796
Q:

What are the Multiples of 6 and the Common Multiples of 4 and 6?

A) 12, 34, 42 B) 12, 18, 36,
C) 6, 4, 14 D) 4, 8, 16
 
Answer & Explanation Answer: B) 12, 18, 36,

Explanation:

The Multiples of 6 are 6, 12, 18, 24, 30, 36, 42, 48, 54, 60.

The Multiples of 4 are 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60.

multiples_4_61517468047.jpg image

The Common Multiples of 4 & 6 upto 60 numbers are given as 12, 24, 36, 48, 60.

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Q:

12 students of class IX took part in GK quiz. If the number of boys is 4 more than the number of girls. Find the number of boys and girls took part in the quiz ?

A) 7, 5 B) 9, 3
C) 8, 4 D) 6, 6
 
Answer & Explanation Answer: C) 8, 4

Explanation:

Let the number of girls = x

=> x + x + 4 = 12

=> 2x = 8

=> x = 4

=> Number of girls = 4

=> Number of boys = 4 + 4 = 8

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16 2933
Q:

A number is 2 more than thrice the second number and 4 times the smaller number is 5 more than the greater number. What is greater number  ?

A) 7 B) 23
C) 9 D) 21
 
Answer & Explanation Answer: B) 23

Explanation:

Let the greater and smaller number be p and q respectively.

4q = p + 5 ------ (I)

p = 3q+2 ------- (II)

From equation (I) and (II)

q = 7

p = 23

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