Bhargav travelled by bus at a speed of $40\mathrm{kmph}$. He then boarded a train which moved at the speed of $60\mathrm{kmph}$ and reached his destination.If the entire distance covered was $150\mathrm{km}$ in a duration of $3\mathrm{hrs}$, then how much distance he travelled by train.

$₹36500$ is deposited into a savings account. After $1$ year $4$ months $15$ days, it totals to $₹42,500$. Calculate the rate of interest for the account.

A person walks at $4 kmph$ and covers a certain distance. If he walks at $9 kmph$ speed, he covers $7.5 km$ more. How much distance did he actually cover at $4 km/h$?