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1. A is faster than B,A and B each walk 24km. The sum of their speeds is 7 km/hr and the sum of times taken by them is 14 hours. Then, A's speed is equal to :
- A. 3 km/hr
- B. 3 km/hr
- C. 3 km/hr
- D. 3 km/hr
Answer: Option C
Explanation:
ধরি, A এর speed x km/hr ; B এর speed =(7-x) km/hr
প্রশ্নমতে, 24/x + 24/7-x= 14
Or, 168-24x + 24x/x(x-7)=14
Or, 168/x(x-7)=14
Or, 98x-14x^2=168
Or, 7x- x^2=12
Or, x^2- 7x + 12= 0
Or, x^2- 4x- 3x -12= 0
Or, x(x-4)-3 (x-4)=0
or, (x-4) (x-3)=0
X-4= 0 অথবা x-3=0
X=4, x=3
অতএব, A is faster than B,
So, A's speed 4 km/hr
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