Mean + reason - practice problems - page 4 of 5
Number of problems found: 81
- Grandfather
The grandfather is three years older than the grandmother. The average age of the grandmother, the grandfather, and their seven grandchildren is 28. The grandchildren have a total of 105 years. Calculate how old grandfather is. - 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? - There
There are 24 students in the class. On Friday, the math class is divided into two groups of 12 students. The table shows the results of pupil assessment in 2 groups. Three students in the 1st group had a worse grade than those in the 2nd group. The other - Hectoliters 4550
The water's surface in the pool is a rectangle 50 meters long and 12 meters wide. The water depth rises evenly from 1 meter at one end of the pool to 3 meters at the other end of the pool (longer sides). Determine the amount of water in the pool in hectol
- Average 4458
The first third of the track was driven by a car at a speed of 15 km/h, the second third at a speed of 30 km/h, and the last third at a speed of 90 km/h. Find the average speed of the car. - Nuts
Peter has 49 nuts. Walnuts have three more than hazelnuts and hazelnut two over almonds. Determine the number of walnuts, almonds, and hazelnuts. - Fifteen
Fifteen students had an average age of 12 years. When the class teacher came to see them, their average increased by exactly one year. How old was the teacher? - Timber log
The ship goes from point x to y. Downstream it takes 4 hours, and upstream 6 hours. How long does it take from a point x to y a log? - Three drivers
Three drivers driving in the same direction found that they have the same amount of gasoline. The first is enough to go 6 km, 4 km, second and third 3km. Gasoline they divided, so all three just drove to the nearest petrol station. How many km away was a
- Remaining 2787
Fifty students took a math test. The average number of points was 68. The top 10 students scored 100 points. What is the average number of points for the remaining 40 students? - Forth and back
Car drive from point A to point B at a speed of 78 km/h and back at 82 km/h. If I went there and back at a speed of 81 km/h journey would take five minutes less. What is the distance between points A and B? - Simultaneously 2570
Two cyclists will set off simultaneously from one place on the circular cycling track. How long before they meet? Do you know that Karel will drive in 6 minutes and Laco in 10 minutes? - Enterprise and wages
The enterprise operates a total 162 workers, and their average salary is M dollars. If the company has hired an additional 18 employee whose average wage would be the S dollars, it will reduce the overall average salary by 3.6%. Calculate the value of the - Target
Peter, Martin, and Jirka were a fire in a particular target, with only three fields with values of 12, 18, and 30 points. All boys were firing with the same number of arrows, and all the arrows hit the target, and the results of every two boys differed by
- Drinking water
A man drinks a keg of water in 36 days, and a woman drinks in 65 days. How many days do they consume a keg together? - Team
The football team has 11 players. Their average age is 20 years. During the match, one player withdraws due to injury, and the team's average age is 18. How old was the injured player? - Pool
If water flows into the pool by two inlets, fill the whole for 20 hours. The first inlet filled the pool 8 hour longer than the second. How long does the pool take to fill with two inlets separately? - Cyclist
The cyclist goes uphill 10 km for 50 minutes and downhill minutes for 29 minutes. Both applied to the pedals with the same force. How long does he pass 10 km by plane? - Energy saving
They released three different independent inventions saving 15%, 17%, and 16% energy. Some considered that while the use of these inventions, the total savings will be 15% + 17% + 16% = 48%. Is this true? How much will the percent of energy save all three
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