# Algebra - problems - page 86

1. I think I think a number. When I multiply it by five, and after that I subtract 477, I get the same number as if I multiplied it twice. What number do I think?
2. Temperature 2 Sunday's high temperature was 3 degrees higher than Saturday's. On Monday, the temperature fell 5 degrees, then rose 7 degrees on Tuesday and 4 more on Wednesday. Then it fell 17 degrees to a record low of 31 on Thursday. What was the temperature on Saturd
3. CuSO4 mixture How many grams of solid CuSO4 we have to add to 450g of 15% CuSO4 solution to produce a 25% solution?
4. Pupils There are 27 pupils in the classroom. They can swim 21 and ski nine pupils. Neither swim nor ski three pupils. How many pupils can swim and ski?
5. Diagonals of a rhombus 2 One diagonal of a rhombus is greater than other by 4 cm . If the area of the rhombus is 96 cm2, find the side of the rhombus.
6. Three students Three students independently try to solve the problem. The first student will solve a similar problem with a probability of 0.6, the second student will solve at a probability of 0.55, and the third will solve at a probability 0.04. The problem is resolved
7. The train The train passed the observer in the 20s and passed through a 1500m tunnel in 2 minutes. Calculate the speed (km/h) and train length.
8. My father My father has a big farm. 6/8 of it were planted with mango trees, 1/2 of the remainder are guava trees and the rest 10 trees are santol trees. What is the number of all trees?
9. Three painters One painter would have painted the fence for 15 hours, the second in 12 hours. The plot had to be painted in four hours, so they called the third one, and all worked together. For what time would the third painter paint fence the fence alone?
10. Car driver The car driver is in town A and is scheduled to be in town B at a specified hour. If it travels at an average speed of 50km/h, it will arrive in city B 30 minutes later. But if he travels at an average speed of 70km/h, he would arrive half an hour earlier
11. Two pipes How long will the pool be filled with a double supply pipe if it takes the pool to fill the first pipe by 4 hours longer and the second pipe 9 hours longer than both pipes open at the same time?
12. Peroxide How many ml 30% of peroxide (H2O2) should be poured into 100ml H2O to give a 20% solution?
13. Dinosaurs More than 30 and less than 60 dinosaurs have met at the pond. A quarter of them bathed and 1/7 saws and the rest gripped. How many were at the pond? How many were there?
14. Children playground The playground has the shape of a trapezoid, the parallel sides have a length of 36 m and 21 m, the remaining two sides are 14 m long and 16 m long. Determine the size of the inner trapezoid angles.
15. 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?
16. The pole The telegraph pole is supported by a 4 m bullet at 3/4 of its height, the end of which is at a distance 2.5 m from the pole post. Calculate the height of the telegraph pole.
17. Rate or interest At what rate percent will Rs.2000 amount to Rs.2315.25 in 3 years at compound interest?
18. Utopia Island A probability of disease A on the island of Utopia is 40%. A probability of occurrence among the men of this island, which make up 60% of all the population (the rest are women), is 50%. What is the probability of occurrence of A disease among women on Uto
19. Diagonals What x-gon has 54 diagonals?
20. Tetrahedron What is the angle of the sides from the base of a three-sided pyramid where the sides are identical?

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