Examples for 8th grade - page 71
- Three ints
The sum of three consecutive integers is 2016. What numbers are they?
Four dwarfs would prepare firewood for Snow White in580 minutes. After an hour and a half they recruit friends so that finished preparing the wood for 280 minutes. How many dwarfs they recruited?
- Unknown number 7
16% of the unknown number is by 21 less than unknown number itself. Determine the natural unknown number.
In the box are yellow (a), green (b) and red (c) peppers. Their amount is in a ratio 2:4:1 . Most are yellow peppers and green the least. Calculate the number of peppers each type if the total number of peppers is 77.
- Even / odd numbers
a / Using variable n write two consecutive odd numbers. b / the sum of three consecutive odd numbers is 333. What are this numbers?
- Direct route
From two different places A and B connected by a direct route, Adam (from city A) and Bohus (from city B) started at a constant speed. As Adam continued to go from A to B, Bohus turned around at the time of their meeting and at the same speed he returned t
- The percentages in practice
If every tenth apple on the tree is rotten it can be expressed by percentages: 10% of the apples on the tree is rotten. Tell percent using the following information: a. in June rained 6 days b, increase worker pay 500 euros to 50 euros c, grabbed 21 fro
- Principal and interest
Peter put € 270 principal into bank and at the end of the year on account was € 282. To what annual interest rate that Peter had deposited money in the bank?
- Triangle angles
In a triangle ABC the interior angle at the vertex C is twice as the internal angle at the point A. Outer angle at the point B measured 117 degrees. How big is the outer angle at the vertex A?
- Bath salts
Bath salt A weighs 900 grams and costs 36,40 CZK. Bath Salts B weighs 1000 grams, but costs 85 CZK. How much is a bath salt A cheaper than B one?
The thickness of a metallic tube is 1cm and its outer radius is 11cm. Find the mass of such 1m long tube, if the density of the metal is 7.5g per cubic cm.
- Eight palm
There grows 8 palms by the sea. At the first sitting one parrot, on second two, on third sits four parrots on each other twice the previous parrots sitting on a previous palm. How many parrots sitting on eighth palm?
- Points on circle
In the Cartesian coordinate system with the origin O is a sketched circle k /O; r=2 cm/. Write all the points that lie on a circle k and whose coordinates are integers. Write all the points that lie on the circle I / O; r=5 cm / and whose coordinates are i
- Six years
In six years Jan will be twice as old as he was six years ago. How old is he?
The city park is a circular bed of flowers with a diameter of 8 meters, around it the whole length is 1 meter wide sidewalk . What is the sidewalk area?
- Cylinder twice
If the radius of the cylinder increases twice, and the height is reduced twice, then the volume of the cylinder increases (how many times?):
Mrs. Violet brewed 15 l of raspberry juice. She poured it into 17 bottles. Some were 3/4 liter and some one liter. How many was bottles of this two types?
- Apples 2
James has 13 apples. It has 30 percent more apples than Sam. How many apples has Sam?
- Tiles path
A rectangular park measures 24mX18m. A path 2.4m wide is constructed all around it. Find the cost of paving the path with cement tiles of size 60cm X 40cm at the rate of $5.60 per tile ?
- Mr and Mrs
Mr. Calda and Mrs. Cald have a total of 139 years. How many years have when we know that Mr. Calda is 9 years older than Mrs. Cald