# Examples for 7th grade (seventh) - page 69

1. Pumps After the floods, four equally powerful pumps exhausted water from the flooded cellar in 6 hours. How many hours would take a drained out with three equally powerful pumps?
2. Magic number The number 135 split to two addends so that one addend was 30 greater than 2/5 the addend.
3. Circle area Calculate the circle area with a radius of 1.2 m.
4. Ratios Reduce the numbers: 50 in a 1:2 ratio 111 at a ratio of 2:3 70 at 10:50 560 at a ratio of 3:8
5. Remainder A is an arbitrary integer that gives remainder 1 in the division with 6. B is an arbitrary integer that gives remainder 2 the division by. What makes remainder in division by 3 product of numbers A x B ?
6. Thunder and lightning There was a glimpse of the sky and we hear a thunder in 4.5 seconds. The light spreads at 300,000 kilometers per second, so we can assume the flash instantly without delay. However, the speed of the sound is much smaller in the air one third of a kilomete
7. Embankment Perpendicular cross-section of the embankment around the lake has the shape of an isosceles trapezoid. Calculate the perpendicular cross-section, where bank is 4 m high the upper width is 7 m and the legs are 10 m long.
8. Unknown number 17 Milada said, I am thinking of a number such that I evaluate expression x1/3, the value of the expression would be 5. Which number Milada thinking?
9. Family 8 Father is 38 years old, daughter 12, son 14. How many years will father have as many years as his children together?
10. Flowers The flower has six flowers and each flower has a number. These are the numbers: 20,40,39,28,8,9. What number will be in the middle of the flower so that the numbers come from the flowers when we subtract and add?
11. Photo enlarge Mark wants to enlarge a 4-inch by 6-inch photo so that it has a height of 15inches. Use a ratio table to determine the new width of the photo.
12. Lcd3 What is LCD of the equation of ? ? And what is x?
13. Candy Peter had a sachet of candy. He wanted to share with his friends. If he gave them 30 candies, he would have 62 candies. If he gave them 40 candies, he would miss 8 candies. How many friends did Peter have?
14. Clubhouse There were only chairs and table in the clubhouse. Each chair had four legs, and the table was triple. Scouts came to the clubhouse. Everyone sat on their chair, two chairs were left unoccupied, and the number of legs in the room was 101. How many chairs w
15. Unknown numbers The sum of two consecutive natural numbers and their triple is 92. Find these numbers.
16. Two cuboids Find the volume of cuboidal box whose one edge is: a) 1.4m and b) 2.1dm
17. Five pumps The water tank is filled with two pumps in 48 minutes. How long would it take to fill it with 5 same pumps?
18. Unknown number I think the number - its sixth is 3 smaller than its third.
19. Bathroom 2 A bathroom is 2.4 meters long and 1.8 meters wide. How many square tiles 1 dm on each side are to be used to cover it?
20. Soda A pack of 12 sodas cost 5.04. What is the unit rate in dollars per soda?

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