A boatman can row his boat at a speed of $8$ km per hour in still water. If a river flows at a speed of $2$ km per hour, then how long will the boatman take to row his boat $1200$ metres against the direction of the current?

Robin purchased an old house for $Rs. 2,75,000$ and his total repairing expense was $Rs. 25,000$. If he sells the house for $Rs. 3,50,000$. What will be his percentage of profit?

An empty tank can be filled with water by one tap in $110$ minutes and by another tap in $132$ minutes. In what time will the tank be filled up completely if both the taps are opened simultaneously?

When a $1.5$ kg weight is hung at one end of a $15$ cm long spring, its length is increased to $16$ cm. What will be the length of the spring when a $6$ kg weight is hung at that end?

Rajeev buys goods worth $Rs. 6,650$. He gets a rebate of $6\%$ on it. After getting the rebate, he pays sales tax $@ 10\%$. Find the amount, he has to pay for the goods.

Three candidates contested an election and received $1136$, $7636$ and $11628$ votes respectively. What percentage of the total votes did the winning candidate get?