Harmonic mean - practice for 14 year olds - page 2 of 5
Number of problems found: 98
- Warehouse 36811
At the Prague Zoo, they need to know how long the fruit will last for the gorillas. The stock in the warehouse would last the female Kamba for 25 days, the male Richard for 20 days, and the little Nura even for 40 days. How long will the supply last if ev - The leaves
Karel raked the leaves in the garden alone in 24 minutes, and his younger brother took 30 minutes. How long would they dig a garden if Karel digs alone for 6 minutes and his brother comes to his aid? - Cleaning 27663
During the pool cleaning, two drains and one inlet were opened. The first outflow would empty the pool in 6 hours, the second outflow would fill it in 9 hours, and the inflow would fill it in 12 hours. How long will it take to empty if the drains are open - Production 24021
The plant has to complete the order in 40 working days. Production takes place in two workshops. In the first one, there are more workers; therefore, they would complete the order themselves in 70 working days. In the second workshop, they would complete
- Simultaneously 17821
The reservoir is filled with the first pump in 30 hours, the second in 24 hours, and the third in 20 hours. How long does it take to fill the reservoir if all pumps are switched on simultaneously? - Aircraft angines
The aircraft's two engines are enough to supply the fuel for five hours of operation. However, one of the engines has malfunctioned 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 of ma - Water current
John swims upstream. After a while, he passes the bottle, and from that moment, he floats for 20 minutes in the same direction. He then turns around and swims back, and from the first meeting with the bottle, he sails 2 kilometers before he reaches the bo - Panel house
The construction company has two groups of workers. Group A has more members than B. Panel house was insulated by group A for ten days. They insulated the same block of flats together in 6 days. How many days would group B block insulate? - Mixture of nuts
We should prepare the mixture of nuts from almonds, peanuts, and nuts cashew ratio of 1:2:3 (respectively). The price of almonds is 150 CZK/kg, the price of peanuts is 140 CZK/kg, and the price of cashew nuts is 180 CZK/kg. The price of the mixture is det
- Average speed
The truck drove 1/2 of the way on the highway at 80km/h. The other half of the way, 20km/h. Calculate the average speed - Reading records
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? - Uphill and downhill
The cyclist moves uphill at a constant speed of v1 = 10 km/h. When he reaches the top of the hill, he turns and passes the same track downhill at a speed of v2 = 40 km/h. What is the average speed of a cyclist? - Four pavers
Four pavers would pave the square in 18 days. How many pavers do you need to add to the done work in 12 days? - Ten cashiers
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?
- Construction 7709
Two construction companies are working on the landscaping. The first would do the whole job in 12 days, the second in 20 days. How long will they work together if the first start working when the second has already worked 4 days? - Kilometers 7684
My father went to dig 6 kilometers of beet at 6:00 pm. It would take him 12 hours. After an hour, the son arrived, and they finished digging at 10:00. How long would it take to dig 6 km of beet for his son? - Tributaries 7678
We filled the pool with two tributaries: the first in 5 hours and the second in 8 hours. The father came and drained 1/8 of the water. How long before the pool fills with both tributaries? - Kilometers 7631
At 8:00, Peter set out on a hike at 5 km/h. At 9:12, Michal followed him on a bike at a speed of 20 km/h. At what time did Michal Petra run, and how many kilometers did he cover? - Two cities
The car goes from city A to city B at an average speed of 70 km/h and back at an average speed of 50 km/h. If it goes to B and back at an average speed of 60 km/h, the whole ride will take 8 minutes less. What is the distance between cities A and B?
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