A) \[3\text{ }km/hr.\]
B) \[4\text{ }km/hr.\]
C) \[5\text{ }km/hr.\]
D) \[7\text{ }km/hr.\]
Correct Answer: B
Solution :
Let, A's speed\[=x\text{ }kmph\]. \[\therefore \] B's speed \[=(7-x)\] kmph Time \[=\frac{\text{Distance}}{Speed}\] According to the question, \[\frac{24}{x}+\frac{24}{7-x}=14\] \[\Rightarrow \] \[24\left( \frac{7-x+x}{x(7-x)} \right)=14\] \[\Rightarrow \] \[\frac{24\times 7}{x(7-x)}=14\] \[\Rightarrow \] \[x(7-x)=12=4\times 3\] or \[3\times 4\] \[\Rightarrow \] \[x(7-x)=4(7-4)\] or \[(7-3)\] \[\Rightarrow \] \[x=4\] or 3 \[\therefore \] A's speed\[=4\text{ }kmph\].You need to login to perform this action.
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