# Examples for 7th grade (seventh) - page 74

1. Is right triangle or not
If right triangle ABC, have sides a=13, b=11.5, c=22.5. Find area.
2. Soldier
An experienced soldier digs a good trench in 30 hours. Two soldiers dug the same trench each 40 hours. How many hours will the ditch dig all three together?
3. Tractors
5 tractors will plow the field for 8 hours. In 2 hours, 1 tractor broke down. How long do the remaining tractors complete the plow?
4. Passenger boat
Two-fifths of the passengers in the passenger boat were boys. 1/3 of them were girls and the rest were adult. If there were 60 passengers in the boat, how many more boys than adult were there?
5. Children's pool
Children's pool at the swimming pool is 10m long, 5m wide and 50cm deep. Calculate: (a) how many m2 of tiles are needed for lining the perimeter walls of the pool? (b) how many hectoliters of water will fit into the pool?
6. Resistance of the resistor
The resistor terminals have a voltage of 20 V and a current of 5 mA is passed through. What is the resistance of the resistor?
7. Seven
Seven friends agree to send everyone a holiday card. How many postcards were sent?
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. Dd 2-digit numbers
Find all odd 2-digit natural numbers compiled from digits 1; 3; 4; 6; 8 if the digits are not repeated.
10. Bus vs train
Milada took the bus and the journey took 55 minutes. Jarmila was 1h 20 min by train. They arrived in Prague at the same time 10h45 min. At what time did each have to go out?
11. 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?
12. 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?
13. Trapezium 2
Trapezium has an area of 24 square cms. How many different trapeziums can be formed ?
14. Orchard
One-eighth of the trees in the fruit plant in winter froze and one-twelfth of damaged disease and pests. Healthy trees remained 152. Is it enough to supply 35 trees to restore the original number of trees in the orchard?
15. Seamstress
The seamstress cut the fabric into 3 parts. The first part was the eighth fabric, the second part was three-fifths of the fabric and the third part had a length of 66 cm. Calculate the original length of the fabric.
16. Sugar production
From 1 ton of beet, 150 kg of sugar is produced. To clean 1 ton of sugar 450 kg of lime is consumed. Calculate how many kgs of lime is consumed when processing 1 ton of sugar beet?
17. Counting number
What is the smallest counting number divisible by 2,5,7,8 and 15?
18. Cuboid
The sum of the lengths of the three edges of the cuboid that originate from one vertex is 210 cm. Edge length ratio is 7: 5: 3. Calculate the length of the edges.
19. Sale
A camera has a listed price of \$751.98 before tax. If the sales tax rate is 9.25%, find the total cost of the camera with sales tax included.
20. Pins 2
how many different possible 4 digits pins can be found on the 10-digit keypad?

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