Smart Math Ex 6
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Smart Math Ex 6 as PDF for free.
More details
- Words: 514
- Pages: 5
Free Example of
Don’t Solve from
© LazyMaths.com
Question A and B have to go from X to Y which are at a distance of 230 kms from each other. A drives at a constant speed of 100 kms/hr for the first 115 kms and then at an average speed of 50 kms/hr for the remaining distance. B starts with an initial speed of 50 kms/hr at X and drives with constant acceleration such that when he reaches Y, his speed is 100 kms/hr. Which of the following statement is true? a. b. c. d. e.
A reaches Y first B reaches Y first A and B reach Y together Cannot calculate from given data None of these
See Next page for Usual Method
2
© LazyMaths.com
Question A and B have to go from X to Y which are at a distance of 230 kms from each other. A drives at a constant speed of 100 kms/hr for the first 115 kms and then at an average speed of 50 kms/hr for the remaining distance. B starts with an initial speed of 50 kms/hr at X and drives with constant acceleration such that when he reaches Y, his speed is 100 kms/hr. Which of the following statement is true? a. b. c. d. e.
A reaches Y first B reaches Y first A and B reach Y together Cannot calculate from given data None of these
The Usual Method A covers half of the distance at 100 kms/hr and the remaining half at 50 kms/hr. 2 × 50 × 100 10000 Hence average speed of A = = = 66.67 kms/hr 50 + 100 150 100 + 50 150 Average speed of B for the whole journey = = = 75 kms/hr 2 2 ∵ Average speed of B > Average speed of A, B will reach Y before A does. (Ans: b) Estimated Time to arrive at the answer = 45 seconds. See Next page for Smart Technique
3
© LazyMaths.com
Question A and B have to go from X to Y which are at a distance of 230 kms from each other. A drives at a constant speed of 100 kms/hr for the first 115 kms and then at an average speed of 50 kms/hr for the remaining distance. B starts with an initial speed of 50 kms/hr at X and drives with constant acceleration such that when he reaches Y, his speed is 100 kms/hr. Which of the following statement is true? A reaches Y first B reaches Y first A and B reach Y together Cannot calculate from given data None of these
a. b. c. d. e.
Using Technique Note that speed of B follows Arithmetic mean and that of A follows Harmonic mean. We know that for a given set of numbers, Harmonic Mean is always < Arithmetic Mean Hence speed of A < speed of B, so B reaches Y before A.
(Ans: b) Estimated Time to arrive at the answer = 10 seconds.
4
© LazyMaths.com
For more Smart Techniques
On
LazyMaths.com
5
© LazyMaths.com
Don’t Solve from
© LazyMaths.com
Question A and B have to go from X to Y which are at a distance of 230 kms from each other. A drives at a constant speed of 100 kms/hr for the first 115 kms and then at an average speed of 50 kms/hr for the remaining distance. B starts with an initial speed of 50 kms/hr at X and drives with constant acceleration such that when he reaches Y, his speed is 100 kms/hr. Which of the following statement is true? a. b. c. d. e.
A reaches Y first B reaches Y first A and B reach Y together Cannot calculate from given data None of these
See Next page for Usual Method
2
© LazyMaths.com
Question A and B have to go from X to Y which are at a distance of 230 kms from each other. A drives at a constant speed of 100 kms/hr for the first 115 kms and then at an average speed of 50 kms/hr for the remaining distance. B starts with an initial speed of 50 kms/hr at X and drives with constant acceleration such that when he reaches Y, his speed is 100 kms/hr. Which of the following statement is true? a. b. c. d. e.
A reaches Y first B reaches Y first A and B reach Y together Cannot calculate from given data None of these
The Usual Method A covers half of the distance at 100 kms/hr and the remaining half at 50 kms/hr. 2 × 50 × 100 10000 Hence average speed of A = = = 66.67 kms/hr 50 + 100 150 100 + 50 150 Average speed of B for the whole journey = = = 75 kms/hr 2 2 ∵ Average speed of B > Average speed of A, B will reach Y before A does. (Ans: b) Estimated Time to arrive at the answer = 45 seconds. See Next page for Smart Technique
3
© LazyMaths.com
Question A and B have to go from X to Y which are at a distance of 230 kms from each other. A drives at a constant speed of 100 kms/hr for the first 115 kms and then at an average speed of 50 kms/hr for the remaining distance. B starts with an initial speed of 50 kms/hr at X and drives with constant acceleration such that when he reaches Y, his speed is 100 kms/hr. Which of the following statement is true? A reaches Y first B reaches Y first A and B reach Y together Cannot calculate from given data None of these
a. b. c. d. e.
Using Technique Note that speed of B follows Arithmetic mean and that of A follows Harmonic mean. We know that for a given set of numbers, Harmonic Mean is always < Arithmetic Mean Hence speed of A < speed of B, so B reaches Y before A.
(Ans: b) Estimated Time to arrive at the answer = 10 seconds.
4
© LazyMaths.com
For more Smart Techniques
On
LazyMaths.com
5
© LazyMaths.com
Related Documents
Smart Math Ex 6
May 2020 6
Smart Math Ex 4
May 2020 8
Smart Math Ex 2
May 2020 4
Smart Math Ex 3
May 2020 8
Smart Math Ex 1
May 2020 7