Harmonic mean + time - math problems

Number of problems found: 74

  • Annual income
    income The annual incomes (in thousands of $) of fifteen families is: 60, 80, 90, 96, 120, 150, 200, 360, 480, 520, 1060, 1200, 1450, 2500, 7200 Calculate harmonic and geometric mean.
  • Weighted harmonic average
    workers_3 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?
  • Two pumps together
    pumps_6 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?
  • Pumping
    pumps_1 The tank is filled with a larger pump in 12 hours and with scond pump in 15 hours. For how long does the tank fill when both pumps are switched on at the same time?
  • Flowerbed
    flowers_9 Ondra digs the bed in 20 minutes. Cuba in 30 minutes. For how long do they dig together?
  • Two pumps
    nadrz_4 The first pump fills the tank in 24 hours second pump in another 40 hours. For how long will it take to fill the tank if it operates both pumps at the same time?
  • 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?
  • Working together
    workers_49 One worker performs work in 3 days, the second in 5 days. How much do they work together?
  • The dam
    prehrada-orlik The water reservoir is filled with first tributary for 25 hours second tributary for 35 hours. Some time were both inlets open, then a second tributary closed and the tank was filled in four hours. What time water flowed from both tributaries? (Expressed
  • Mow the lawn
    grass_2 Dano would mow the lawn in 12 hours and Milada in 16 hours. How long will take the lawn mow together?
  • Two rooms
    clean_1 Woman cleans the room in 30 minutes a man in 90 minutes. How long will take they clean two rooms?
  • Working together
    malovka_1 One painter paint the nursery in 10 days, the second in 8 days. How many days will the nursery be painted if they work together?
  • Soldier
    digging_1 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?
  • Water current speed.
    river_4 Two cities along the river are 100 km apart. The powerboat downstream runs for 4 hours, upstream for 10 hours. Determines the river's current speed.
  • Timber log
    water3 The ship goes from point x to y. Downstream it takes 4 hours, upstream 6 hours. How long does it take from a point x to y a log?
  • Three pumps
    pumps_5 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?
  • Cleaners
    clean Milan would clean up the room for 2.5 hours, Eric would take 10 hours. How long they swept the room together?
  • Workers
    workers Two workers fulfill a certain task when working together for 5 days, the first if he worked himself done work in 13 days. How many days will do whole job a second worker?
  • Bricklayers
    delnik_4 When a bricklayer works himself to redeem the house in 8 days, the other bricklayer will be finished in 10 days. How long will it take to make 3 such houses together?
  • Painter Pavel
    pixla_s_farbou Painter Pavel painted the fence for 16 hours and painter Petr the same fence painted for 13 h. How long should take painted the fence together?

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