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ব্যাংক নিয়োগ প্রস্তুতি ⎯ লং কোর্স

পরীক্ষাব্যাংক নিয়োগ প্রস্তুতি ⎯ লং কোর্সতারিখতারিখ অনির্ধারিতসময়30 minutes
মোট প্রশ্ন২১
সিলেবাস
Math - 01: Number System, Problems on Number, HCF & LCM
ঘনত্ব
উত্তর
উত্তরিতবর্তমানপুনরায় দেখুনঅসম্পূর্ণ

ব্যাংক নিয়োগ প্রস্তুতি ⎯ লং কোর্স

ব্যাংক নিয়োগ প্রস্তুতি ⎯ লং কোর্স · তারিখ অনির্ধারিত · ২১ প্রশ্ন

.
Add 2√2 + 5√3 and √2 - 4√3
  1. ক) √2 + 2√3
  2. খ) 2√2 + 2√3
  3. গ) 3√2 + √3
  4. ঘ) 3√2 + 3√3
সঠিক উত্তর:
গ) 3√2 + √3
উত্তর
সঠিক উত্তর:
গ) 3√2 + √3
ব্যাখ্যা
(2√2 + 5√3) + (√2 - 4√3)
= (2 + 1)√2 + (5 - 4)√3
= 3√2 + √3
.
The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 36. What is the difference between the two digits of that number?
  1. ক) 4
  2. খ) 5
  3. গ) 6
  4. ঘ) 7
সঠিক উত্তর:
ক) 4
উত্তর
সঠিক উত্তর:
ক) 4
ব্যাখ্যা
Let
the ten's digit be x 
unit's digit be y.

Then,
(10x + y) - (10y + x) = 36
9(x - y) = 36
x - y = 4
.
Which of the following has the most number of divisors?
  1. ক) 99
  2. খ) 101
  3. গ) 182
  4. ঘ) 176
সঠিক উত্তর:
ঘ) 176
উত্তর
সঠিক উত্তর:
ঘ) 176
ব্যাখ্যা
Divisors of 99 are 1, 3, 9, 11, 33, .99
Divisors of 101 are 1 and 101
Divisors of 176 are 1, 2, 4, 8, 11, 16, 22, 44, 88 and 176
Divisors of 182 are 1, 2, 7, 13, 14, 26, 91 and 182.

Hence, 176 has the most number of divisors.
.
Three times the first of three consecutive odd integers is 3 more than twice the third. The third integer is:
  1. ক) 11
  2. খ) 13
  3. গ) 15
  4. ঘ) 17
সঠিক উত্তর:
গ) 15
উত্তর
সঠিক উত্তর:
গ) 15
ব্যাখ্যা
Let
The three integers be x, x + 2 and x + 4.

Then,
3x = 2(x + 4) + 3      
3x = 2x + 8 + 3
3x - 2x = 11
x = 11.

Third integer = x + 4 = 11 + 4 = 15
.
Which of the following numbers should be added to 8567 to make it exactly divisible by 4?
  1. ক) 4
  2. খ) 1
  3. গ) 2
  4. ঘ) 3
সঠিক উত্তর:
খ) 1
উত্তর
সঠিক উত্তর:
খ) 1
ব্যাখ্যা
On dividing 8567 by 4, the remainder is 3.

To make it divisible by 4, we must add (4 - 3) =1 
.
The product of two numbers is 9375 and the quotient, when the larger one is divided by the smaller, is 15. The sum of the numbers is:
  1. ক) 420
  2. খ) 400
  3. গ) 450
  4. ঘ) 600
সঠিক উত্তর:
খ) 400
উত্তর
সঠিক উত্তর:
খ) 400
ব্যাখ্যা
Let
the larger numbers be x and
the smaller numbers be y.

Then, xy = 9375 and
          x/y = 15
now 
xy/(x/y) = 9375/15
y2 = 625
y2 = 252
y = 25 

x = 25 × 15 = 375

x + y = 375 + 25 = 400
.
The HCF and LCM of two numbers are 24 and 168 and the numbers are in the ratio 1 ∶ 7. Find the greater of the two numbers.
  1. ক) 168
  2. খ) 250
  3. গ) 124
  4. ঘ) 136
সঠিক উত্তর:
ক) 168
উত্তর
সঠিক উত্তর:
ক) 168
ব্যাখ্যা
Given that 
HCF = 24
LCM = 168
Ratio of numbers = 1 ∶ 7. 
Let numbers be x and 7x.

We know 
Product of numbers = LCM × HCF
 x × 7x = 24 × 168
⇒ x2 = 24 × 24
⇒ x = 24
∴ Larger number = 7x
                            = 24 × 7
                             = 168
.
HCF of two number is 4 and the sum of those two numbers is 36. Find how many such pair of number is possible.
  1. ক) 1
  2. খ) 2
  3. গ) 3
  4. ঘ) 4
সঠিক উত্তর:
গ) 3
উত্তর
সঠিক উত্তর:
গ) 3
ব্যাখ্যা
HCF of two number is 4
Let, those numbers be 4x and 4y where x and y are prime to each other Accordingly,
4x + 4y = 36
⇒ 4(x + y) = 36
⇒ (x + y) = 9
Now,
9 = 8 + 1
9 = 7 + 2
9 = 6 + 3
9 = 5 + 4
In all these cases only (8, 1); (7, 2); and (5, 4) are prime to each other.
So, such three pair is possible
∴ Such three pair of number is possible.
 
To find the pairs we only can take those pair, which are prime to each other. 
We can't take those pair, which are not prime to each other. 
For example: In this problem, 9 can be represent as 6 + 3 = 9 
But, 6 & 3 are not prime to each other. 
So, it can't be a possible pair.
.
What is the sum of two consecutive even numbers, the difference of whose squares is 84?
  1. ক) 40
  2. খ) 42
  3. গ) 44
  4. ঘ) 46
সঠিক উত্তর:
খ) 42
উত্তর
সঠিক উত্তর:
খ) 42
ব্যাখ্যা
Let
the numbers be x and x + 2.

Then,
(x + 2)2 - x2 = 84
x2 + 2.x.2 + 22 - x2 =84
4x + 4 = 84
4x = 80
x = 20.

The required sum = x + (x + 2)
                             = 2x + 2
                             = (2 × 20) + 2
                             = 42
১০.
Find the least number which when divided by 20, 25, 35, and 40 leaves remainders 14, 19, 29 and 34 respectively. 
  1. ক) 1400
  2. খ) 1394
  3. গ) 1406
  4. ঘ) 1384
সঠিক উত্তর:
খ) 1394
উত্তর
সঠিক উত্তর:
খ) 1394
ব্যাখ্যা
Here
20 − 14 = 6
25 − 19 = 6
35 − 29 = 6
40 − 34= 6

Required number (L.C.M of 20, 25, 35, and 40) - 6

L.C.M of 20, 25, 35, and 40 = 1400
Required number= 1400 - 6 = 1394
১১.
What is the least perfect square that is a multiple of 7, 11 and 12?
  1. ক) 421231
  2. খ) 242131
  3. গ) 223121
  4. ঘ) 213444
সঠিক উত্তর:
ঘ) 213444
উত্তর
সঠিক উত্তর:
ঘ) 213444
ব্যাখ্যা
Let us assume the least perfect square be X
⇒ 7 = 7 × 1
⇒ 11 = 11 × 1
⇒ 12 = 22 × 3 ⇒

The LCM of (7, 11, 12) = 22 × 3 × 11 × 7
⇒ The least perfect square = 22 × 32 × 112 × 72 = 213444
∴ The required result will be 213444.
১২.
The sum of two numbers is 40 and their difference is 4. The ratio of the number is 
  1. ক) 12 : 13
  2. খ) 11 : 9
  3. গ) 11 : 10
  4. ঘ) 10 : 11
সঠিক উত্তর:
খ) 11 : 9
উত্তর
সঠিক উত্তর:
খ) 11 : 9
ব্যাখ্যা
Given:
The sum of two numbers is 40.
The difference of two number is 4.
Let
the larger number be x.
 the smaller number be y.
According to the question,
(x + y)/(x - y) = 40/4 
(x + y)/(x - y) =10/1
10(x - y) = x + y
10x - 10y = x + y
10x - x = 10y + y
9x = 11y 
x/y = 11/9
x : y = 11 : 9 

∴ The ratio of the number is 11 : 9
১৩.
The number of times 99 is subtracted from 1111 so that the remainder is less than 99 is -
  1. ক) 10
  2. খ) 11
  3. গ) 12
  4. ঘ) 13
সঠিক উত্তর:
খ) 11
উত্তর
সঠিক উত্তর:
খ) 11
ব্যাখ্যা
On dividing 1111 by 99, the quotient is 11 and the remainder is 22.
Hence, the required number is 11
১৪.
6*2 is three digit number with * as a missing digit. If the number is divisible by 6, the missing digit is
  1. ক) 6
  2. খ) 3
  3. গ) 7
  4. ঘ) 2
সঠিক উত্তর:
গ) 7
উত্তর
সঠিক উত্তর:
গ) 7
ব্যাখ্যা
Divisibility of 6 = Number should be multiple of 3 and 2
6*2 it is definitely divisible by 2
To be divisible by 3 Sum of all digits of the number be divisible by 3
We just try to put value in place of *
632 = 6 + 3 + 2 = 11(not divisible by 3)
662 = 6 + 6 + 2 = 14(not divisible by 3)
672 = 6 + 7 + 2 = 15( divisible by 3)
622 = 6 + 2 + 2 = 10(not divisible by 3)
∴ * is replaced by 7
১৫.
The L.C.M. of (6x2 - x - 1), (3x2 + 7x + 2) and (2x2 + 3x - 2) is
  1. ক) (2x - 1) (3x + 1) (3x + 2)
  2. খ) (2x - 1) (3x + 1) (x - 2)
  3. গ) (2x + 1) (3x - 1) (x + 2)
  4. ঘ) (2x - 1) (3x + 1) (x + 2)
সঠিক উত্তর:
ঘ) (2x - 1) (3x + 1) (x + 2)
উত্তর
সঠিক উত্তর:
ঘ) (2x - 1) (3x + 1) (x + 2)
ব্যাখ্যা
6x2 - x - 1 = 6x2 - 3x + 2x - 1
                = 3x(2x - 1) + 1(2x - 1)
                 = (2x - 1) (3x + 1)


(3x2 + 7x + 2) = 3x2 + 6x + x + 2
                      = 3x(x + 2) + 1(x + 2)
                       = (x + 2)(3x + 1)

(2x2 + 3x - 2) = 2x2 + 4x - x - 2
                      = 2x(x + 2) - 1(x + 2)
                      = (x + 2) (2x - 1)

∴ Required L.C.M. is = (2x - 1) (3x + 1) (x + 2)
১৬.
Three numbers are in the ratio of 3 : 4 : 5 and their L.C.M is 2400. Their H.C.F is 
  1. ক) 30
  2. খ) 40
  3. গ) 50
  4. ঘ) 60
সঠিক উত্তর:
খ) 40
উত্তর
সঠিক উত্তর:
খ) 40
ব্যাখ্যা
Let us consider the number be 3x,4x and 5x
The L.C.M of the three numbers be =60x
60x = 2400
x = 2400/60
x = 40

Then the number be
3x = 3 × 40 = 120
4x = 4 × 40 = 160
5x = 5 × 40 = 200

∴ The HCF of the three numbers be 40
১৭.
Out of six consecutive natural numbers if the sum of the first three is 30, what is the sum of the other three?
  1. ক) 36
  2. খ) 39
  3. গ) 42
  4. ঘ) 45
সঠিক উত্তর:
খ) 39
উত্তর
সঠিক উত্তর:
খ) 39
ব্যাখ্যা
Let
the first three consecutive numbers be x, x + 1 and x + 2.
Then, 
x + x + 1 + x + 2 = 30
⇒ 3x + 3 = 30
⇒ 3x = 27
⇒ x = 9
∴ The first three numbers are  9, 10,11
⇒ The next three numbers are 12, 13, 14.
Hence, the required sum =12 + 13 + 14
                                        = 39
১৮.
If the numbers from 1 to 24, Which are divisible by 2 are arranged in descending order, which will be at the 7th place from the bottom?
  1. ক) 12
  2. খ) 14
  3. গ) 16
  4. ঘ) 18
সঠিক উত্তর:
খ) 14
উত্তর
সঠিক উত্তর:
খ) 14
ব্যাখ্যা
The descending order of the number from 1 to 24  which are divisible by 2 is:
24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2
Now count the 7th place number from the right.

The number will be at the 8th place from the bottom is 14.
১৯.
One-fifth of a number is equal to 5/8 of another number . If 35 is added to the first number, it becomes four times of the second number. The second number is-
  1. ক) 35
  2. খ) 42
  3. গ) 40
  4. ঘ) 38
সঠিক উত্তর:
গ) 40
উত্তর
সঠিক উত্তর:
গ) 40
ব্যাখ্যা
Let 
the numbers be a and b.
According to the problem,
the first equation is:
a/5=5b/8
a/5=5b/8
25b = 8a
a = 25b/8

   a + 35=4b
⟹a = 4b − 35
(25b/8) - 4b = - 35 
(25b - 32b)/8 = - 35 
- 7b/8 = -35
b = (35 × 8)/7
b = 40
২০.
A number whose fifth part increased by 4 is equal to its fourth part reduced by 10. Find the number.
  1. ক) 260
  2. খ) 270
  3. গ) 280
  4. ঘ) 290
সঠিক উত্তর:
গ) 280
উত্তর
সঠিক উত্তর:
গ) 280
ব্যাখ্যা
Let
the number be x
According to problems condition 
(x/5) + 4 = (x/4) - 10
(x/5) - (x/4) = - 10 - 4
(4x - 5x)/20 = - 14
-x/20 = - 14 
x = 280
২১.
If the three numbers are added in pairs , the sum is equal to 10, 16, 24. What is the difference between third and first number?
  1. ক) 5
  2. খ) 6
  3. গ) 7
  4. ঘ) 8
সঠিক উত্তর:
খ) 6
উত্তর
সঠিক উত্তর:
খ) 6
ব্যাখ্যা
Let,
the numbers are a, b and c
According to the question,
⇒ a + b = 10
⇒ b + c = 16
⇒ c + a = 24

From above question,
⇒ 2(a + b + c) = 50
⇒ (a + b + c) = 25
Value of a = 25 - (b + c) = 25 - 16 = 9
Value of c = 25 - (a + b) = 25 - 10 = 15

Required difference = (15 - 9) = 6
∴ Difference is 6