781 . A certain river has a current of 3 miles per hour. A boat takes twice as long to travel upstream between two points as it does to travel downstream between the same two points. What is the speed of the boat in still water?

A. 3 miles per hour
B. 6 miles per hour
C. 9 miles per hour
D. 12 miles per hour

View Answer	Favorite Question

Answer: Option C

Explanation:

Let the boat speed and current flow be U and V respectively. According to the question, the relative speed of boat downstream (U + V) is twice as that of upstream (U - V).

So, U + V = 2(U - V)

or, U + V = 2U - 2V

or, 2U - U = V + 2V

or, U = 3V = 3 x 3 = 9 km per hour

প্রিমিয়াম প্ল্যান: ১ মাস

99 ৳

৩০ দিনের জন্য সকল লাইভ এবং আর্কাইভ মডেল টেস্ট, প্রশ্ন ব্যাংক ও লেকচার শিট সহ অ্যাপ এর প্রিমিয়াম সব এক্সেস পাবেন।

সাবস্ক্রিপশন লিংক

782 . A certain river has a current of 4 miles per hour.A boat takes twice as long to travel upstream between two points as it does to travel downstream between the same two points . What is the speed of the boat in still water ?

A. 6 miles per hour
B. 8 miles per hour
C. 12 miles per hour
D. cannot be determined

View Answer	Favorite Question

Answer: Option C

Explanation:

Let, boat speed is x

ATQ

X+4=2(x-4)

X+4=2x-8

X=12

783 . A certain sum of money at simple interest amount to Tk.1012 in 5/2 years and Tk.1067.20 in 4 years, the rate of interest per annum is--

A. 4%
B. 5%
C. 2.5%
D. 3%

View Answer	Favorite Question

Answer: Option A

Explanation:

784 . A certain sum of money consists of 30 coins, some of which are 10 paisa coins and the rest are 5 paisa coins. If the total value of the coins is Tk.2, what is the number of 10 paisa coins?

A. 10
B. 15
C. 12
D. 8

View Answer	Favorite Question

Answer: Option A

Explanation:

x = number of 10 paisa coins;

y = number of 5 paisa coins .

so,x + y = 30

and x = 30 - y

ATQ,

10x + 5y = 200

Substitute for x.

10(30 - y) + 5y = 200

or,300 - 10y + 5y = 200

or, - 5y = - 100

or,y = 20

so,x = 30 - 20 = 10

∴ the number of 10 paisa coins is 10

785 . A certain type of wall for a house costs Tk. 10.50 per square yard. What does it cost to make a wall 4 yards wide and 60 feet long?

A. Tk. 800
B. Tk. 840
C. Tk. 2520
D. Tk. 3240

View Answer	Favorite Question

Answer: Option B

Explanation:

60 feet = 20 yards

area of wall = 4 yards * 20 yards = 80 square yard

1 square yard require = 10.50 tk

80 square yard require = 10.50*80 = 840 tk (Ans)

786 . A chemist is mixing acid and water. Out of the 30 ml mixed such that a 50/50 mixture of water and acid is attained if no additional water is added?

A. 20
B. 10
C. 40
D. 30

View Answer	Favorite Question

Answer: Option B

Explanation:

To achieve a 50/50 mixture of water and acid, you need to add an equal amount of water to the existing 10 ml of acid. Since you have 30 ml of the mixture, which already contains 10 ml of acid, you need to add an additional 10 ml of water (equal to the amount of acid) to balance it out. So, the answer is 10 ml.

787 . A circle and a rectangle have the same perimeter. The sides of the rectangle are 18 cm and 26 cm. what is the area of the circle?

A. 1250 sq. cm
B. 616 sq. cm
C. 154 sq. cm
D. 88 sq. cm

View Answer	Favorite Question

Answer: Option B

Explanation:

The sides of the rectangle are 18 cm and 26 cm.

Circle and a rectangle have the same perimeter.

Now,

2πr= 2(18+26)

πr= 44

22/7 ×r = 44

r= 14

Area of the circle= πr^2 = πr×r = 44×14 = 616

Ans: 616 sq. cm

বাংলাদেশ ব্যাংক || সহকারী পরিচালক (AD) (20-10-2023)

A. 12x
B. 48x
C. 24x
D. 36x

View Answer	Favorite Question

Answer: Option B

Explanation:

For smaller wheel,

Circumference = 2×π×28/2 = 28π

Revolve in 1 second = x times

Revolve in 60 seconds = 60x times

So, distance = 28π×60x

For larger wheel,

Circumference = 2×π×35/2 = 35π

Let,

Revolve per minute = n

So, distance = 35πn

Now,

28π×60x = 35πn

Or, n = (28π × 60x)/35π

Or, n = 48x

789 . A circular flower bed has diameter 4m. The flower bed is increased so that the diameter is now 12 m. How many times longer is the new flower bed?

A. 9
B. 3
C. 32
D. 8

View Answer	Favorite Question

Answer: Option A

Explanation:

790 . A circular grass walk of 2 feet wide surrounded a pond of 100 fet in diameter. In terms of π, how many square feet grass walk are there?

A. 204 π
B. 102 π
C. 404 π
D. 202 π

View Answer	Favorite Question

Answer: Option A

Explanation:

791 . A circular logo is enlarged to fit the lid of a jar. The new diameter is 50 percent larger than the original. By what percentage has the area of the logo increased?

A. 50
B. 80
C. 100
D. 125
E. None of these

View Answer	Favorite Question

Answer: Option D

Explanation:

792 . A circular swimming pool is to be filled with water. If the radius of the pool is 2m and the height of the pool is 7m, what volume of water will be required to fill the pool ?

A. 88m^3
B. 176m^3
C. 25.14m^3
D. none of these

View Answer	Favorite Question

Answer: Option A

Explanation:

Volume

=πr²h

=(22/7)×2²×7

=88m³

(ans)

793 . A circular wheel 28 inches in diameter rotates (moves) the same number of inches per second as a circular wheel 35 inches in diameter. If the smaller wheel makes x revolutions per second, how many revolutions per minute does the larger wheel make in terms of x?

A. 12x
B. 48x
C. 24x
D. 36x
E. None of these

View Answer	Favorite Question

Answer: Option B

Explanation:

Let the revolutions made by larger wheel per minute be R.

Circumference of smaller wheel, 2 π r = 2 x π x (28/2) = 28π

Circumference of larger wheel, 2 π r = 2 x π x (35/2) = 35π

Speed of smaller wheel per minute = 60x

Distance covered by larger wheel per minute = Distance covered by smaller wheel per minute

or, R x 35π = 28π x 60x

or, R = 28π x 60x / 35π = 48x

794 . A circular wheel 28 inches in diameter rotates the same number of inches per second as a circular wheel 35 inches in diameter. If the smaller wheel makes x revolutions per second, how many revolutions per minutes does the larger wheel make in terms of x?

A. 12x
B. 24x
C. 36x
D. 48x

View Answer	Favorite Question

Answer: Option D

Explanation:

ছোট চাকার ব্যাস = 28 ইঞ্চি

ছোট চাকার ব্যাসার্ধ r1 = 28/2 = 24 ইঞ্চি

ছোট চাকার পরিধি = 2πr1 = 28π ইঞ্চি

বড় চাকার ব্যাস = 35 ইঞ্চি

বড় চাকার ব্যাসার্ধ r2 = 35/2 ইঞ্চি

বড় চাকার পরিধি = 2πr2 = 2 × π × 35/2 = 35π ইঞ্চি

ছোট চাকাটি x বার ঘুরে যায় = 28πx ইঞ্চি

ছোট চাকাটি 1 সেকেন্ডে যায় = 28 πx ইঞ্চি

ছোট চাকাটি 60 সেকেন্ডে যায় = ( 60 × 28πx) = 1680πx ইঞ্চি

বড় চাকাটি 1 মিনিটে ঘুরবে = 1680πx /35π = 48x বার।

795 . A cistern can be filled in 10 hours but it takes 12 hours due to a leak in its bottom. If the cistern is full, then the time that the leak will take to empty it is:

A. 60 min
B. 80 h
C. 90 h
D. 60 h

View Answer	Favorite Question

Answer: Option D

Explanation:

781 . A certain river has a current of 3 miles per hour. A boat takes twice as long to travel upstream between two points as it does to travel downstream between the same two points. What is the speed of the boat in still water?

782 . A certain river has a current of 4 miles per hour.A boat takes twice as long to travel upstream between two points as it does to travel downstream between the same two points . What is the speed of the boat in still water ?

783 . A certain sum of money at simple interest amount to Tk.1012 in 5/2 years and Tk.1067.20 in 4 years, the rate of interest per annum is--

784 . A certain sum of money consists of 30 coins, some of which are 10 paisa coins and the rest are 5 paisa coins. If the total value of the coins is Tk.2, what is the number of 10 paisa coins?

785 . A certain type of wall for a house costs Tk. 10.50 per square yard. What does it cost to make a wall 4 yards wide and 60 feet long?

786 . A chemist is mixing acid and water. Out of the 30 ml mixed such that a 50/50 mixture of water and acid is attained if no additional water is added?

787 . A circle and a rectangle have the same perimeter. The sides of the rectangle are 18 cm and 26 cm. what is the area of the circle?

788 . A circle wheel 28 inches in diameter rotates the same number of inches per second as a circular wheel 35 inches in diameter. If the smaller wheel makes x revolutions per second, how many revolutions per minute does the larger wheel make in terms of x?

789 . A circular flower bed has diameter 4m. The flower bed is increased so that the diameter is now 12 m. How many times longer is the new flower bed?

790 . A circular grass walk of 2 feet wide surrounded a pond of 100 fet in diameter. In terms of π, how many square feet grass walk are there?

791 . A circular logo is enlarged to fit the lid of a jar. The new diameter is 50 percent larger than the original. By what percentage has the area of the logo increased?

792 . A circular swimming pool is to be filled with water. If the radius of the pool is 2m and the height of the pool is 7m, what volume of water will be required to fill the pool ?

793 . A circular wheel 28 inches in diameter rotates (moves) the same number of inches per second as a circular wheel 35 inches in diameter. If the smaller wheel makes x revolutions per second, how many revolutions per minute does the larger wheel make in terms of x?

794 . A circular wheel 28 inches in diameter rotates the same number of inches per second as a circular wheel 35 inches in diameter. If the smaller wheel makes x revolutions per second, how many revolutions per minutes does the larger wheel make in terms of x?

795 . A cistern can be filled in 10 hours but it takes 12 hours due to a leak in its bottom. If the cistern is full, then the time that the leak will take to empty it is:

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