Harmonic mean + work - math problems

Number of problems found: 64

  • Workshops
    workers The plant has three workshops. In the first workshop, produce 5 products/hour, in the second 8 products/hour, and in the third 7 products/hour. In the first workshop, they produced 240 products, in the second 400 and the third 350 products. Find the avera
  • Weighted harmonic average
    workers Ten workers will do some work in 2 minutes, five workers in 10 minutes and three workers in 6 minutes. How many minutes per average worker per worker?
  • The leaves
    garden Karel would rake the leaves in the garden alone in 24 minutes, his younger brother would take 30 minutes. How long would they dig a garden, if Karel digs alone for 6 minutes and then his brother comes to his aid?
  • Aircraft angines
    aircraft-02 The two engines of the aircraft are enough to supply the fuel for five hours of operation. However, one of the engines has a malfunction and thus consumes one-third more fuel. How long can the plane be in the air before it runs out of fuel? After an hour
  • Panel house
    workers The construction company has two groups of workers. Group A has more members than B. Panel house was insulated by group A in 10 days. They insulated the same block of flats together in 6 days. How many days would group B block insulate?
  • Reading records
    clock-night-schr Lucy, Tereza, and Petra decided to compile the compulsory reading records together. It would take 30 days for Lucia alone, 36 for Tereza and 45 for Petra. How long will it take to make records if they will work together?
  • Four pavers
    tiles2 Four pavers would pave the square in 18 days. How many pavers do you need to add to done work in 12 days?
  • Ten cashiers
    pokladna Ten cashiers are open at Tesco. Customers wait an average of 15 minutes. How many other cashiers have to open to reduce the waiting time by 4 minutes?
  • Flowerbed
    flowers Ondra digs the bed in 20 minutes. Cuba in 30 minutes. For how long do they dig together?
  • Two pumps together
    pumps The first pump will fill the tank itself in 3 hours and the second one in 6 hours. How many hours will the tank be full if both pumps are worked at the same time?
  • Three pumps
    pumps We are filling the pool. The first pump would be filled in 12 hours, the second pump in 15 hours. If all three pumps were running at the same time, it would fill the pool for 4 hours. How long would the pool fill only with the third pump?
  • Working together
    workers One worker performs work in 3 days, the second in 5 days. How much do they work together?
  • The factory
    clocks The factory z can complete an order in 12 days, factory p in 18 days. How many days does an order completed when the first two days work only the factory z and then both factories?
  • Water reservoir
    nadrz One drain hole emptied the water from the tank for 20 hours, with the second drain for 30 hours. How long will the water drain from this tank if we open two drains simultaneously?
  • Harvesters
    kombajn The first harvester will harvest the grain from the field in 20 hours, the second, the more powerful in 10 hours. How long will it take to harvest this field by both harvesters if the second harvester has to be set up first and this takes 2 hours? The fir
  • A report
    work Maricris can type a committee report in 5 hours. Jane helped Maricris and together they finished the report in 3 hours. How long would it take Jane to complete the report she had worked alone?
  • Soldier
    digging An experienced soldier digs a good trench in 30 hours. Two soldiers dug the same trench each 40 hours. How many hours will the ditch dig all three together?
  • Summer tires
    workers Three tire servants have to change the summer tires on 6 cars in 2 hours. Mark's replacement would take 4.5 hours, Jirka would do it in 3 hours and 10 minutes, and Honza in 4 hours. Will they be able to replace all tires at the desired time?
  • Evening shift
    workers While working the evening shift, Officer K took 8 hours to complete a task at his work station and Officer M took 10 hours to complete the same task at his work station. How many hours would it take Officer K and Officer M to complete the same task workin
  • Together 3
    painter If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?

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