Class 10 Exam  >  Class 10 Questions  >  A plane left 40 minutes late due to bad weath... Start Learning for Free
A plane left 40 minutes late due to bad weather and in order to reach it's destination, 1600 km away in time,it had to increase it's speed by 400 km/h from it's usual speed. Find the usual speed of the plane :
  • a)
    600 km/h
  • b)
    750 km/h
  • c)
    800 km/h
  • d)
    None of these
Correct answer is option 'C'. Can you explain this answer?
Most Upvoted Answer
A plane left 40 minutes late due to bad weather and in order to reach ...
Solution:-

Distance = 1600 km

Let the usual speed be = x km/h

now we know that 

speed = distance /time

time = distance / speed

Usual time = 1600/x

Now due to bad weather the speed is increased be 400 km/ hr

which means new speed = 1600/x+400

Now it's given that the plain left 40 minutes late

which means new time = 1600/x+400 + 2/3 ( 40/60 = 2/3 hours)

1600/x = 1600/x+400 +2/3

1600/x-1600/x+400 = 2/3

1600(x+400)-1600x)/x(x+400) = 2/3

1600x + 640000-1600x/x²+400x = 2/3

640000 = 2/3(x²+400x)

640000 * 3/2 = x²+400x

960000 = x² +400x

0 = x²+400x-960000

0 = x² +1200x-800x-960000

0 = x( x+ 1200) - 800(x+1200)

0= (x+1200)(x-800)

x= -1200 or x= 800

Speed cannot be negative 
∴ usual speed = 800 km/h
Free Test
Community Answer
A plane left 40 minutes late due to bad weather and in order to reach ...
Problem Solving Strategy:
- Use the formula:
Distance = Speed x Time
- Calculate the time taken to cover 1600 km at usual speed and increased speed.
- Use the time difference to find the usual speed.

Solution:
Let the usual speed of the plane be 'S' km/h.
The distance to be covered is 1600 km.
The time taken to cover the distance at the usual speed is:
Time = Distance / Speed
Time = 1600 / S hours
Due to bad weather, the plane left 40 minutes late. So the time available to cover the distance is:
Time = (1600 / S) - (40 / 60) hours
Time = (1600 / S) - (2 / 3) hours
The plane needs to cover the distance in time, so the time taken at the increased speed is:
Time = 1600 / (S + 400) hours
The difference in time taken at usual speed and increased speed is 40 minutes or 2/3 hours.
(1600 / S) - (2 / 3) - (1600 / (S + 400)) = (2 / 3)
Multiplying both sides by S(S+400) we get:
1600(S+400) - 2S(S+400)/3 -1600S = 2S(S+400)/3
Simplifying the above equation, we get:
S = 800 km/h

Therefore, the usual speed of the plane is 800 km/h. Hence, option (c) is the correct answer.
Attention Class 10 Students!
To make sure you are not studying endlessly, EduRev has designed Class 10 study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Class 10.
Explore Courses for Class 10 exam

Top Courses for Class 10

A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer?
Question Description
A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? for Class 10 2024 is part of Class 10 preparation. The Question and answers have been prepared according to the Class 10 exam syllabus. Information about A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Class 10 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer?.
Solutions for A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Class 10. Download more important topics, notes, lectures and mock test series for Class 10 Exam by signing up for free.
Here you can find the meaning of A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer?, a detailed solution for A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? has been provided alongside types of A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice A plane left 40 minutes late due to bad weather and in order to reach its destination, 1600 km away in time,it had to increase its speed by 400 km/h from its usual speed. Find the usual speed of the plane :a)600 km/hb)750 km/hc)800 km/hd)None of theseCorrect answer is option 'C'. Can you explain this answer? tests, examples and also practice Class 10 tests.
Explore Courses for Class 10 exam

Top Courses for Class 10

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev