Maths practice for 14 year olds - page 356 of 361
Number of problems found: 7215
- Gold wire
A wire of length 1.4 km was drawn from one gram of gold. What is its diameter if the density of gold is ρ = 19.5 g/cm³? - Energy saving
Three independent inventions were released, each saving 15%, 17%, and 16% of energy respectively. Some people assumed that using all three would save 15% + 17% + 16% = 48% of energy. Is this correct? What is the actual total percentage of energy saved by - Bulbs
A box contains 16 bulbs of 75 W, 14 bulbs of 40 W, and 10 bulbs of 50 W. Calculate the probability that a randomly selected bulb is: a) 40 W b) 75 W or 40 W - The angle of lines
Calculate the angle between the two lines y = x-8 and y = +12. - Median
In the right triangle are sides a=96 dm b=31 dm. Calculate the length of the medians tc to the hypotenuse. - Rectangles
How many rectangles with an area of 8855 cm² have sides that are natural numbers? - Secret number
Find the secret number n, which reversed decreases by 15.4 if the number increases by 15.4. - Rectangle SS
The perimeter of a rectangle is 154 dm and its diagonal is 62.36 dm. Find the dimensions of the rectangle. - Track arc
Two straight railway tracks meet at an angle of 126°. They are joined by a circular arc with radius r = 1110 m. How long is the connecting arc (L)? How far is the centre of the arc from the intersection of the tracks (x)? - Seedcake
Seedcake costs 20 cents. How many minimum seedcakes must we buy that we can pay in cash, only whole euros? - Sphere slices
Calculate the volume and surface area of a sphere if two parallel circular cross-sections have radii r₁ = 32 cm and r₂ = 47 cm, and the distance between them is v = 21 cm. - Sphere cuts
At what distance from the centre does a plane intersect a sphere of radius R = 46, if the area of the circular cross-section and the area of the great circle are in the ratio 2:5? - Heron backlaw
Calculate the length of the unknown side of a triangle with sides 39 and 38 and area 438.6. - Triangle
Calculate all three altitudes of triangle ABC with sides a = 26, b = 81, and c = 73. - Diamond
Find the side length of a rhombus whose area is S = 194 cm² and one diagonal is u₂ = 44 cm. - Cone and cube
About what percentage has cone with base radius r larger volume than a same high cube with square base with edge length r? - The cap
A jester's hat is in the shape of a cone. Calculate how much paper is needed to make a hat 53 cm tall for a head circumference of 45 cm. - Cable car
A cable car rises at an angle of 44° and connects the upper and lower stations with an altitude difference of 1089 m. How long is the continuous (endless) tow rope? - Trigonometry
Given that cos(γ) = sin(806°), find the angle γ. - Steeple
A church tower is seen from the road at an elevation angle of 52°. When we move back a further 29 metres, it is seen at an elevation angle of 21°. How tall is the tower?
Do you have homework that you need help solving? Ask a question, and we will try to solve it. Solving math problems.
