Examples for 8th grade - page 13
- Two workers
The first worker completed the task by himself in 9 hours, the second in 18 hours. After two hours of joint work left first worker to a doctor and the second finished the job himself. How many hours worked second worker himself?
7.4 meters long ladder is leaning against the wall of the well and its lower end is 1.1 meters from this wall. How high from the bottom of a well is the top edge of the ladder?
Welder do the job for six hours, the second one for 8 hours. How long do the job third welder if all together can do job in 2 hours?
- Percent chaining
Calculate 20% from 70% from 80 km
- Logik game
Letter game Logik is a two player game, which has the following rules: 1. The first player thinks five-letter word in which no letter is not repeated. 2. The second player writes a five-letter word. 3. The first player answers two numbers - the first numbe
From 117 children who participated in the ski course were 24 excellent skiers, 26 good and 26 average and the rest were beginners. Calculate this data in percentages.
- Is equal
Is equal following terms? ?
- Digging companies
Company A would dig a pit for 12 days, company B for 15 days, company C for 20 days and the company D for 24 days. Work began together companies C and D, but after three days joined them other two companies. How long took to dig a pit?
- Spherical cap
From the sphere of radius 12 was truncated spherical cap. Its height is 4. What part of the volume is spherical cap from whole sphere?
Pediatrician this month of 21 working days takes 3 days holidays. What is the probability that on Monday will be at work?
Bottle with cork cost 9.9 Eur. The bottle is 0.9 euros more expensive than cork. How much is a bottle and the cork?
- Diagonal in rectangle
In that rectangle ABCD is the center of BC point E and point F is center of CD. Prove that the lines AE and AF divide diagonal BD into three equal parts.
- Five girls
Five girls traveling by bus. Each holds in each hand two baskets. In each basket are four cats. Each cat has three kittens. Two girls exits bus. How many legs are in the bus?
The point (21, 20) is on the terminal side of angle θ. cos θ = ?
- Oil rig
Oil drilling rig is 23 meters height and fix the ropes which ends are 8 meters away from the foot of the tower. How long are these ropes?
- Cars plates
How many different licence plates can country have, given that they use 3 letters followed by 4 digits?
The lenght, width and height of a right prism are 18, 14 and 9 respectively. What is the lenght of the longest segment whose endpoints are vertices of the prism?
How many 46% alcohol we need to pour into 3 liters 63% alcohol to get p3% of the alcohol? How many 52% alcohol we get?
What angle are between directions W (West) and SE (SouthEast) on the compass?
In the Hockey World Cup play eight teams, determine how many ways can they win gold, silver and bronze medals.