Subject
Quantitative Aptitude
Topic
Speed & Distance
A train normally travels 60 miles at a certain speed. On a day, due to mechanical problem, the train's speed is reduced by 10 mph so that the journey takes 3 hours longer. What is the normal speed of the train?
A train normally travels 60 miles at a certain speed. On a day, due to mechanical problem, the train's speed is reduced by 10 mph so that the journey takes 3 hours longer. What is the normal speed of the train?
ক)
20খ)
25গ)
32ঘ)
45ঙ)
none of theseExplanation
QUESTION: একটি train সাধারণত একটি নির্দিষ্ট গতিতে 60 miles যাত্রা করে। একদিন, যান্ত্রিক সমস্যার কারণে, train-এর গতি 10 mph কমে যায়, যার ফলে যাত্রা 3 ঘণ্টা বেশি সময় নেয়। train-এর স্বাভাবিক গতি কত? সমাধান: *চলক নির্ধারণ: -ধরি, x = train-এর স্বাভাবিক গতি (mph) *সমীকরণ স্থাপন: -স্বাভাবিক যাত্রার সময়: 60/x ঘণ্টা -কমানো গতি: (x - 10) mph -নতুন যাত্রার সময়: 60/(x-10) ঘণ্টা *প্রদত্ত তথ্য ব্যবহার: -60/(x-10) - 60/x = 3 *সমীকরণ সমাধান: -60x/(x(x-10)) - 60(x-10)/(x(x-10)) = 3 -(60x - 60x + 600)/(x(x-10)) = 3 -600/(x(x-10)) = 3 -600 = 3x(x-10) -600 = 3x^2 - 30x -0 = 3x^2 - 30x - 600 -0 = x^2 - 10x - 200 -(x - 20)(x + 10) = 0 -x = 20 অথবা x = -10 (ঋণাত্মক সমাধান বাদ দিন) -train-এর স্বাভাবিক গতি 20 mph অতএব, সঠিক উত্তর হল (A) 20 mph। train-এর স্বাভাবিক গতি 20 mph।Related questions
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