Explain solution RD Sharma class 12 Chapter 29 Linear Programming exercise 29.4 question 36
Answer: The maximum that the man can travel in 1 hr. is 30km. Distance travelled at the speed of 25km/hr is km and 40 km/hr. is km
Hint:
Let us assume that the man travels xkm/hr. and y km when the speed is 40km/hr.
Given:
Speed of vehicle=25km/hr.
Per km cost on petrol=2Rs/km
Young man carries only =100 Rs.
Solution:
Let us assume that the man travels x km when the speed is 25km/hour and y km when the speed is 40km/hour.
Thus, the total distance travelled is (x+y) km.
Now, it’s given that the man has 100Rs to spend on petrol.
Total cost of petrol=
Now, Time taken to travel x km = hour
Time taken to travel y km = hour
Now it’s given that the maximum time is 1 hour. So,
Thus, the given linear programming problem is
Maximize Z=x+y
Subject to the constraints
The feasible region determined by the given constraints can be diagrammatically represented as,
The coordinates of the corner points of region are O(0,0), A(25,0), B(50/3,40/3) and C(0,20).
The value of objective function at these points are given in the following
Corner Points |
Z=x+y |
(0,0) |
0+0=0 |
(25,0) |
25+0=25 |
(50/3,40/3) |
50/3+50/3=30 |
(0,20) |
0+20=20 |
So the maximum value of Z is 30 at
Thus, the maximum distance that the man can travel in one hour 30 km
Hence, the distance travelled by the man at the speed of 225 km/hr is 50/3 km and the distance travelled by him at the speed of the 40km/hour is 40/3 km.