Aptitude- Numerical Word Problems- Work Rate

In a popular music channel songs are played uninterrupted (i.e. no commercial breaks). If each song lasts between 2.5 and 6 minutes, how many songs will be played during a full hour?

The manager at the country club decided to build an additional Olympic pool for VIPs only. When the pool was ready to be filled with water, the manager opened a pipe that fills a pool within 12 hours. A new lifeguard who was eager to help out opened a second pipe which turned out to be a draining pipe which empties a full pool within 18 hours. By how many hours would the filling process be delayed?

Two workers at a farm have been busy for the past week, arranging all the hay stacks into tidy bundles. The farmer was very pleased with their work and asked them to pile the 120 bundles they have made in the barn. If worker A piles 30 bundles in 20 minutes and worker B piles 17 bundles in half an hour, how long will it take them to complete the work?

Joanna and James decided to invite 30 friends over for dinner. They went that morning to the market in order to get fresh groceries; James bought 6 Kg of vegetables for a salad and Joanna bought beans and meat for her famous chili con carne. Whilst James cuts 1.5 Kg of vegetables, Joanna prepares 7 portions of chili. How many portions of chili did Joanna prepare whilst James finished cutting 5.2 Kg of vegetables?

The great city of "Yellow Breaks" has 10 parks which are attended by the city's gardeners. Towards the annual gardening competition between cities, the mayor was informed by his personal advisor that 4 gardeners with identical work-rate are allocated to each park for 1 hour per day. The mayor, pondering about ways to win the competition, asked his advisor how long will it take for the same amount of work to be done by 12 gardeners in each park?

A reputed architect is looking to hire a group of workers to carry out his newest design. The architect received many applications and has managed to narrow down the list to two highly- recommended groups. Since the architect has to stick to a very tight timetable he would like to choose the group which will accomplish the project the fastest. In order to make a decision he asks group A how long will it take them to build 12 stories and he asks group B how long will it take them to build 27 stories? They replied the following:
Group A - weeks
Group B - 7.5 weeks
Both groups have the same amount of workers.
Which group should the architect choose for his ravishing 121 stories high project?

A toy factory has three machines that wrap all the toys in boxes. All three machines work at the same rate and finish wrapping a certain amount of toys in 48 hours. If a fourth machine with the same rate were to be added, what would be the new total time of work?

Two round balls are sliding down a smooth slope at constant speeds. Ball A rotates at 12 revolutions per minute and ball B rotates at 57 revolutions per minute. If both balls were thrown (i.e. began rotating) at the same time, how many seconds will pass until ball B has completed exactly 6 more revolutions than ball A?

There are six printers at "Today's news" newspaper, each printing at the same constant rate. Working together, the six printers can complete printing tomorrow's newspaper within 12 hours. If the owner wishes to reduce the printing time to 8 hours, how many additional printers, each with the same constant rate, will he need to purchase?

Tom completes a given task in 20 days whilst Joan requires only 12 days in order to complete the same task. Tom and Joan set out to complete one task together. They started to work at the same time; however, due to personal reasons Joan had to take a leave of absence of 4 days during their mutual work. If Tom continued working on his own during Joan's leave, how many days did it take them to complete the task?