Math practice for 13 year olds - page 411 of 427
Number of problems found: 8528
- Sea water
Seawater contains about 6.5% salt. How many dm³ of distilled water must we pour into 21 dm³ of seawater to get water with 1.2% salt? - Steamship
Between the two ports on the river is going steamship. The journey there and back takes 12:53. Downstream steamship traveling at 19 km/h, upstream 8 km/h. What is the distance between the ports? - Reflector
The circular reflector throws a light cone with a vertex angle 56° and is on 24 m height tower. The axis of the light beam has the axis of the tower angle 11°. What is the maximum length of the illuminated horizontal plane? - Monty Hall
Suppose you're on a game show and have the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. What is the - Workers
Two workers would fulfill a certain task when working together for 10 days, the first if he worked himself done work in 17 days. How many days will the second worker do the whole job? - Pillar
Calculate the volume of a pillar in the shape of a regular quadrilateral frustum (truncated pyramid) with base edges a = 10 and b = 19, and height h = 28. - 4s pyramid
A regular tetrahedral pyramid has a base edge a=8 and a collateral edge length b=20. What is its height? - Tetrahedral pyramid
What is the surface of a regular tetrahedral (four-sided) pyramid if the base edge a=16 and height v=16? - Perpendicular
What is the slope of the perpendicular bisector of line segment AB if A[-1,-4] and B[-6,-7]? - ABS
What is the value of ||-48|-|-29||? - Triangle
For how many integer values of x can 16, 10, and x be the lengths of the sides of a triangle? - Parallelogram
Calculate area of the parallelogram ABCD as shown if |AB| = 13 cm, |BC| = 99 cm and angle BAD = 100° - Segments
Which of the pairs of numbers on the number line encloses the longest segment: ... - Root
The root of the equation $eq is (equal or greater or less than zero). $radio - Cone
If the segment of the line y = -2x +3 that lies in the first quadrant is rotated about the y-axis, a cone is formed. What is the volume of the cone? - Prism
A right prism's length, width, and height are 17, 11, and 11, respectively. What is the length of the longest segment whose endpoints are vertices of the prism? - Negative percentage
In 2006, the company had a loss of 11100 Euros. Two years later, he was already in profit 50000 Eur. Calculate the percentage of the company's profits that increased in these two years. - Drinking water
A man drinks a barrel of water in 21 days, and a woman drinks in 43 days. How many days do they consume a barrel together? - Forestry workers
84 laborers have been employed to plant trees in the forest. For 9 hour work a day, they would end job in 38 days. After 18 days, 6 laborers leave. How many days are needed to complete planting trees in nurseries by others if they work 12 hours a day? - Stairway
What angle rising stairway if the step height is 20 cm and the width 26 cm?
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