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2 gun shots were fired at an interval of 38 minutes. A person approaching the firing point hears the two sounds at an interval of 36 minutes. If speed of sound is 330m/sec then find the speed of car in km/hr. Query is: why can't I follow the below approach Distance covered by gun in 38 minutes= distance covered by gun in 36 minutes + distance covered by man in 2 minutes. 330×18/5 (38/60) = 330×18/5 (36/60) + speed of man ×(2/60) Thanks

2 gun shots were fired at an interval of 38 minutes. A person approaching the firing point hears the two sounds at an interval of 36 minutes. If speed of sound is 330m/sec then find the speed of car in km/hr.
 
Query is: why can't I follow the below approach
Distance covered by gun in 38 minutes= distance covered by gun in 36 minutes + distance covered by man in 2 minutes.
330×18/5 (38/60) = 330×18/5 (36/60) + speed of man ×(2/60)
 
Thanks

Grade:8

1 Answers

Sourabh Singh IIT Patna
askIITians Faculty 2104 Points
7 years ago
hii

You have to consider that the time between them is reduced by 2 minutes which means if the person would have been still he would have heard the shots after 38 mins but no he was moving towards the gun .

So the distance covered by car reduced the overall distance between them by 2 mins.

Use this you will get the answer

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