Math practice for 13 year olds - page 17 of 423

Number of problems found: 8443

Offset the mean
The mean of 16 numbers is 8. If 2 is added to every number, what will be the new mean?
Plasticine cuboid
Paul makes a cuboid of plasticine with sides 5 cm, 2 cm, and 5 cm. How many such cuboids will he need to form a cube?
To percentages
Convert the following ratios to percentages. (a) 3 : 4 (b) 2 : 3 (c) 5/8 (d) 15/16
Overtime and salary
An employee earns R150 per hour, and the agreed normal working hours are 45 hours per week. Overtime is paid at 1 1/2 of the normal rate. Suppose Dave works 52 hrs during the first week of March. What will the total earnings for that particular week be?
Double sides
If each side of a triangle is doubled, then find the ratio of the area of the new triangle thus formed to the given triangle.
Taps and a tank
A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?
Manday, manhour
Job problem: 10 men can make 20 toys in 12 days working 12 hours a day.Then, in how many days can 24 persons make 32 toys working 16 hours a day?
Tricky result
Classic adding with percentages: Evaluate 28% of 450 + 45% of 280
Two chords 6
A chord PQ is 10.4cm long, and its distance from the center of a circle is 3.7cm. Calculate the length of a second chord RS, which is 4.1cm from the center of this circle.
Numerator and denominator
If the numerator of a fraction is increased by 200% and the denominator of the fraction is increased by 150%, the resultant fraction is 9/35. What is the original fraction?
Two coins
Two coins are tossed simultaneously. What is the probability of getting (i) At least one head? (ii) At most one tail? (iii) A head and a tail?
Katy bought
Katy bought 4/5 kg of oranges, 2 1/2 kg of bananas, and 1 1/2 kg of apples every day. How many kilograms of fruit did she buy each day?
Walnuts 2
There are 6 2/3 pounds of walnuts in a container, which will be divided equally into containers that hold 1 1/2 pounds. How many containers will walnuts fill?
The marathon
Twelve athletes are joining the Topolcany Marathon Event. How many ways can the first, second, and third placers be chosen?
A rope
A 75m piece of rope needs to be cut in a ratio of 1:4. What is the length of each piece?
Closer to one
Here are two sums: A=1/2 + 1/3 and B=1/5 + 1/3. Which of the two sums is closer in value to 1? You must show your work and state clearly whether the answer is A or B.
Lara's sequence
Lara starts with a number less than 20. She divides it by 2 and adds 6. She then divides this result by 3. Her answer is 4.5. What number does she start with?
Empty rooms
In the tourist dormitory, 44 students slept in eight rooms, some of which were four-bed and others six-bed. When two beds were empty, how many four-bed and six-bed rooms were there in the dormitory?
One muffin
Eight muffins and one drink cost $8.12. If the drink costs $1.24, find the cost of one muffin.
Mixed numbers equation
4 5/9 is the same as the sum of 2 1/3 and 5/6 times a number. What is the number? Enter your answer as a mixed number in simplest form in the box.

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