# Examples for 8th grade - page 14

- TVs

Production of television sets increased from 3,500 units to 4,200 units. Calculate the percentage of production increase. - Swimming pool 4

The pool shaped cuboid measuring 12.5 m × 640 cm at the bottom is 960hl water. To what height in meters reaches the water level? - 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. - Conference

97 is the total number of employees. The conference was attended by 34 employees. How much is it in percent? - Waiting room

In the waiting room are people and flies. Together they have 15 heads and 50 legs (fly has 6 legs). How many people and flies are in the waiting room? - Pizza

A school survey found that 9 out of 16 students like pizza. If 5 students are chosen at random, what is the probability that all 5 students like pizza? - Hurry - rush

At an average speed 10 km/h I will come from the school to the bus stop for 29 minutes. How fast I need to go if I need to get to the bus stop in 21 minutes? - Buses

Buses Ikarus and Karosa simultaneously started at 11:00 from the final station. Ikarus is returned to the station after 30 minutes. Karosa after 45 minutes. At what time both buses again returned to the station? - Unknown x

If we add to unknown number 72, then divide by 2 and then subtract 29, we get back an unknown number. What is this unknown number? - Square

Calculate area of the square with diagonal 70 cm. - Chess

How many ways can select 3 fields on classic chess board with 64 fields, so that fields don't has the same color? - Cleaners

Milan would clean up the room for 2.5 hours, Eric would take 10 hours. How long they swept the room together? - Gasholder

The gasholder has spherical shape with a diameter 23 m. How many m^{3}can hold in? - Air

Room is 26.2 m long, 23.4 dm wide and 628 cm high. How many people can simultaneously be in this room if for hygiene reasons is calculated 5100 dm^{3}of air per person? - Class

In a class are 32 pupils. Of these are 8 boys. What percentage of girls are in the class? - Expressions

Expression (3a-7).(3a+7) is identical with: ? - Parachutists

Parachutists during freefall firstly held in groups of 4, then of 6, then 9, 12 and finally of 18 members. How many parachutists jump at least should be, if at each group must all be involved. - Reciprocal

What is the reciprocal of the sum of the reciprocals of 7 and 2? - Ladislav in Amsterdam

Ladislav was reward and went to conference in Amsterdam. Conferense fee was € 2184. Calculate how many books Ladislav could buy at the price of 42 and 28 euros if he don't want fill whole home library and he can buy only 63 books? - Birthdate

Jane on birthday brought 30 lollipops and 24 chewing gum for their friends. How many friends has, if everyone receives the same number of lollipops and chewing gums? How much chewing gum and lollipops got any friend?

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