Themes, topics - math word problems

Working alone
Tom and Chandri are doing household chores. Chandri can do the work twice as fast as Tom. If they work together, they can finish the work in 5 hours. How long does it take Tom working alone to do the same work?
Accelerated motion - mechanics
The delivery truck with a total weight of 3.6 t accelerates from 76km/h to 130km/h in the 0.286 km long way. How much was the force needed to achieve this acceleration?
Three pumps together
One pump fills the tank in 1.5 hours, the second in 2 hours, and the third in 3 hours 20 minutes. How many minutes will the tank fill with three pumps if they work simultaneously?
Two water containers
In the first container, there are 200 m³ of water and in the second 40 m³. The first container will flow down at a rate of 10 m³ water per hour. At the same time flows to the second rate of 5 m³ per hour. After how many hours there will be three times less
Two math problems
1) The sum of twice a number and -6 is nine more than the opposite of that number. Find the number. 2) A collection of 27 coins, all nickels, and dimes, is worth $2.10. How many of each coin are there? The dime, in United States usage, is a ten-cent coin
Martha
Martha likes to walk in the park, the park is square, 7/10 mi on each side. One morning Martha walked around the entire park 3 1/2 times before stopping to rest. How far had she walked?
Copper sulphate
How much g of water do we have to add to 240 g of an 84% CuSO4 solution to produce a 60% solution? (Express the mass of crystalline CuSO4 in the original solution and in the resulting solution and compare them. )
Records
Records indicate 90% error-free. If 8 records are randomly selected, what is the probability that at least 2 records have no errors?

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