Mean + expression of a variable from the formula - practice problems - page 4 of 5
Number of problems found: 98
- A report
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 on alone? - Minutes 7177
The tank holds 140 liters of water. The tank is filled with a tap in 5 minutes, and the drain is emptied in 7 minutes. How long will it take for the empty tank to fill if we open the faucet and drain? - Center of line segment
Calculate the distance of point X [1,3] from the center of the line segment x = 2-6t, y = 1-4t; t is from interval <0,1>. - Soldier
An experienced soldier digs a good trench in 30 hours. Two soldiers dug the same trench every 40 hours. How many hours will the ditch dig all three together?
- Summer tires
Three tire servants must change the summer tires on six 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
While working the evening shift, Officer K took 8 hours to complete a task at his workstation, and Officer M took 10 hours to complete the same task at his workstation. How many hours would it take Officer K and M to complete the same task, each working a - Test scores
Jo's test scores on the first four 100-point exams are as follows: 96,90,76, and 88. If all exams are worth the same percentage, what is the minimum test score necessary on his last exam to earn an A grade in the class (90% or better)? - Together 3
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? - Trochanters 6743
The 9th graders combed hops. They worked a few hours on the first day and combed a total of x trochanters of hops. On the second day, they combed for b hours and combed y trochanters. How long did it take them to comb one trochanter on average? Express wi
- Three painters
The three painters have painted bridges. The first would work done in 5 days, the second in 6 days, and the third in 7.5 days. How long will the bridge work if they work together? - Young mathematician
One young mathematician was bored again. He found that the average age of people in the room where the seminar equals its count. Then his 29-year-old brother entered the room. Even then, the average age of all present was the same as the count of people. - Twenty-three-year-old 6317
The average age of the first five hockey players was 22 years. The coach replaced the twenty-three-year-old player with a younger one, which lowered the average age of the first five hockey players to 21 years. How old is the new player? - Three pumps
The water tank is emptied with the first pump in 6 hours, with the second pump in 2 hours. In order to be emptied in 1 hour, all three pumps had to be started at once. How long will it take to empty the tank by only the third pump? - Flying
The airplane from Prague to Bratislava was flying at a speed of 60 km/h less and back by 70 km/h greater than the original speed. What was the original speed if the plane returned to Prague according to the timetable?
- In and out
The empty tank is filled in 12 minutes and empty in 16 minutes. How long does it take to fill if we forget to close the drain? The tank has 1000 liters of volume. - Average age
The average age of all people at the celebration was equal to the number of people present. After the departure of one person who was 29 years old, the average age was again equal to the number present. How many people were original to celebrate? - ICE train
German runways test a new ICE train between Munich and Berlin. The train runs to Berlin at a slow speed of 100 km/h. Back from Berlin goes faster. How quickly did the train have to go on a return trip so that the average train speed for both journeys woul - Doctor 2
A doctor noted the Diastolic Blood Pressure (DBP) of a large number of patients. Later, he scrambled the data to keep the privacy of his patients. Based on the scrambled dataset, he finds that the lower inner fence is equal to 50 and the upper inner fence - Oil tank and pipes
Two oil pipelines can fill the underground oil tank. The first is filled in 72 hours, and the second in 48 hours. How many hours from when the first pipeline began to fill the oil is necessary to start filling it with the second to fill in 1 and 1/2 days?
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