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HEY MATE!
________________________☆
HERE IS YOUR ANSWER:
STEP BY STEP EXPLANATION:
We , are given that police runs after thief after 1 minute
Speed of the thief is given as 100km/min
Speed of the police is given in A.P i.e 100, 110,120,130..
Now, as the police catches the thief at a common place,
So,Let Time taken by the thief be x+1 min
and time taken by police to reach that place will be x (as police is 1 min late)
Now, speer of police= 100+110+120+130.....till t minutes
Sum of the speed of police = distance of police=n/2[2a+(n-1)d)]
St=t/2[2(100)+(t-1)10]
St=t/2[200+(t-1)10]
St=t/2[10(20+t-1]
St=10t/2(19+t)
St=5t(19+t)
Now, distance of police=distance of thief (as thief was caught by police at a distance)
distance of thief=100(t+1)
Now, 5t(19+t)=100(t+1)
t(10+t)=20(t+1)
19t+t^2=20t+20
0=t^2+19t-20t-20
t^2-t-20=0
t^2-5t+4t-20=0
t(t-5)+4(t-5)=0
(t-5)(t+4)=0
t=5,-4
Time cannot be negative , hence the time taken to catch the thief is 5 min.
______________________☆
HOPE IT HELPED ^_^
________________________☆
HERE IS YOUR ANSWER:
STEP BY STEP EXPLANATION:
We , are given that police runs after thief after 1 minute
Speed of the thief is given as 100km/min
Speed of the police is given in A.P i.e 100, 110,120,130..
Now, as the police catches the thief at a common place,
So,Let Time taken by the thief be x+1 min
and time taken by police to reach that place will be x (as police is 1 min late)
Now, speer of police= 100+110+120+130.....till t minutes
Sum of the speed of police = distance of police=n/2[2a+(n-1)d)]
St=t/2[2(100)+(t-1)10]
St=t/2[200+(t-1)10]
St=t/2[10(20+t-1]
St=10t/2(19+t)
St=5t(19+t)
Now, distance of police=distance of thief (as thief was caught by police at a distance)
distance of thief=100(t+1)
Now, 5t(19+t)=100(t+1)
t(10+t)=20(t+1)
19t+t^2=20t+20
0=t^2+19t-20t-20
t^2-t-20=0
t^2-5t+4t-20=0
t(t-5)+4(t-5)=0
(t-5)(t+4)=0
t=5,-4
Time cannot be negative , hence the time taken to catch the thief is 5 min.
______________________☆
HOPE IT HELPED ^_^
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