Subject
Quantitative Aptitude
Topic
Speed & Distance
A person travels from P to Q at a speed of 40 kmph and returns by increasing his speed by 50% . What is his average speed for both the trips?(একজন ব্যক্তি P হতে Q স্থানে 40 kmph বেগে গেল এবং 50% বর্ধিত বেগে পূর্বের স্থানে ফিরে আসল । উভয়ক্ষেত্রে তাঁর গড়বেগ কত?)
A person travels from P to Q at a speed of 40 kmph and returns by increasing his speed by 50% . What is his average speed for both the trips?(একজন ব্যক্তি P হতে Q স্থানে 40 kmph বেগে গেল এবং 50% বর্ধিত বেগে পূর্বের স্থানে ফিরে আসল । উভয়ক্ষেত্রে তাঁর গড়বেগ কত?)
ক)
36 kmphখ)
45 kmphগ)
48 kmphঘ)
50 kmphExplanation
ধরি, P ও Q এর মধ্যবর্তী দূরত্ব x P থেকে Q তে যাওয়ার সময় বেগ 40 km/hr 40 km/hr এর 50% = {(50/100)×40 km/hr } = 20 km/hr ∴ Q থেকে P তে আসার সময় বেগ = (40+20) km/hr = 60 km/hr ∴ P থেকে Q তে যেতে সময় = (x/40) hr [ সময় = দূরত্ব/বেগ ] Q থেকে P তে ফেরত আসতে সময় = (x/60) hr [ সময়=দূরত্ব/বেগ] ∴ যাওয়া-আসা মিলে মোট সময় = {(x/40)+(x/60)} hrs ∴ গড়বেগ = (মোট দূরত্ব/মোট সময়) = [2x/{(x/40)+(x/60)}] = [ 2x/{(60x+40x)/40×60)} ] ={ (2×40×60)/(40+60) }= 48 km/hrRelated questions
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