Problem: In a flight of 600km, an aircraft was slowed down due to bad weather. its average speed for the trip was reduced by 200kmflrr and the time of flight increased by 30 minutes. Find out the duration of the flight.
View all: RUPALI BANK(RB) | WRITTEN QUESTION (MATH) SOLVE | 2013
Correct Answer: ans: 1.5 hour
Explanation:
Here, Distance, D = 600kmLet, Time = t & Speed = s
According to the question,
=>D = st
=>600 = st
=>s=$\frac{600}{t}$
From 2″” condition,
=>(s-200)$(t+\frac{1}{2})$=600
=>($\frac{600}{t}$-200)$(t+\frac{1}{2})$=600
=>($\frac{600-200}{t}$)($\frac{2t+1}{2})$)=600
=>(600 + 200t) (2t + 1) = 600
=>1200t + 600 – 400$t^{2}$ – 200t=1200t
=>600 – 400$t^{2}$ – 200t= 0
=>400$t^{2}$ + 200t- 600 = 0
=>4$t^{2}$ +2t -6 =0
=>2$t^{2}$ + t – 3 = o
=>(2t+3)(t-1)=0
=>t = l and t= -$\frac{3}{2}$
As, t cannot be negative,
So, t = 1 hour
Duration of the journey = Normal time + Extra/Delay
= 1h + 0.5h = 1.5 hour
