Defence Exam > Defence Questions > A boat goes 15 km upstream and 10 ½ km...
Start Learning for Free
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?
- a)4
- b)6
- c)10
- d)14
Correct answer is option 'C'. Can you explain this answer?
| FREE This question is part of | Download PDF Attempt this Test |
Verified Answer
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15...
Let speed of the boat in still water be x km/h and speed of current be y km/h. Then, upstream speed = (x – y) km/h and downstream speed = (x + y) km/h Now,
From Equation (i) and (ii) x = 10 km/hr and y = 4 km/hr.
From Equation (i) and (ii) x = 10 km/hr and y = 4 km/hr.
Most Upvoted Answer
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15...
Km downstream in a total of 5 hours. If the speed of the boat in still water is 30 km/h, what is the speed of the current?
Let's assume the speed of the current is x km/h.
When the boat goes upstream, its effective speed is reduced by the speed of the current, so it is (30 - x) km/h. The distance traveled upstream is 15 km. Therefore, the time taken to go upstream is 15 / (30 - x) hours.
When the boat goes downstream, its effective speed is increased by the speed of the current, so it is (30 + x) km/h. The distance traveled downstream is 10 km. Therefore, the time taken to go downstream is 10 / (30 + x) hours.
The total time taken for the entire trip is 5 hours, so we can write the equation:
15 / (30 - x) + 10 / (30 + x) = 5
To solve this equation, we can first get rid of the denominators by multiplying every term by (30 - x)(30 + x):
15(30 + x) + 10(30 - x) = 5(30 - x)(30 + x)
Expanding and simplifying:
450 + 15x + 300 - 10x = 5(900 - x²)
750 + 5x = 4500 - 5x²
Rearranging the terms:
5x² + 5x - 3750 = 0
Dividing every term by 5:
x² + x - 750 = 0
Now we have a quadratic equation. We can solve it by factoring or using the quadratic formula. By factoring, we find:
(x - 25)(x + 30) = 0
This gives us two possible values for x: x = 25 or x = -30. Since the speed cannot be negative, the speed of the current is 25 km/h.
Let's assume the speed of the current is x km/h.
When the boat goes upstream, its effective speed is reduced by the speed of the current, so it is (30 - x) km/h. The distance traveled upstream is 15 km. Therefore, the time taken to go upstream is 15 / (30 - x) hours.
When the boat goes downstream, its effective speed is increased by the speed of the current, so it is (30 + x) km/h. The distance traveled downstream is 10 km. Therefore, the time taken to go downstream is 10 / (30 + x) hours.
The total time taken for the entire trip is 5 hours, so we can write the equation:
15 / (30 - x) + 10 / (30 + x) = 5
To solve this equation, we can first get rid of the denominators by multiplying every term by (30 - x)(30 + x):
15(30 + x) + 10(30 - x) = 5(30 - x)(30 + x)
Expanding and simplifying:
450 + 15x + 300 - 10x = 5(900 - x²)
750 + 5x = 4500 - 5x²
Rearranging the terms:
5x² + 5x - 3750 = 0
Dividing every term by 5:
x² + x - 750 = 0
Now we have a quadratic equation. We can solve it by factoring or using the quadratic formula. By factoring, we find:
(x - 25)(x + 30) = 0
This gives us two possible values for x: x = 25 or x = -30. Since the speed cannot be negative, the speed of the current is 25 km/h.
|
Explore Courses for Defence exam
|
|
Similar Defence Doubts
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer?
Question Description
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? for Defence 2024 is part of Defence preparation. The Question and answers have been prepared according to the Defence exam syllabus. Information about A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Defence 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer?.
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? for Defence 2024 is part of Defence preparation. The Question and answers have been prepared according to the Defence exam syllabus. Information about A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Defence 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer?.
Solutions for A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Defence.
Download more important topics, notes, lectures and mock test series for Defence Exam by signing up for free.
Here you can find the meaning of A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of
A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer?, a detailed solution for A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? has been provided alongside types of A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? theory, EduRev gives you an
ample number of questions to practice A boat goes 15 km upstream and 10 ½ km downstream in 3 hours 15 minutes. It goes 12 km upstream and 14 km downstream in 3 hours. What is the speed of the boat in still water?a)4b)6c)10d)14Correct answer is option 'C'. Can you explain this answer? tests, examples and also practice Defence tests.
|
|
Explore Courses for Defence exam
|
|
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
|
© EduRev
|
Education Revolution
|
Follow Us
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup