Merry-Go-Round
Find the area of a circle with a diameter of 10 cm. Use 3.14 as PI.
How far did Mr Tan travel at a speed of 70km/h for 2.5hr?
70 X 2.5 = 175 km
Sally ate 1/2 of a pie while her 3 siblings share the rest of the pie. What is the fraction of the pie for each sibling?
1/2 divides by 3 = 1/2 X 1/3 = 1/6
Find the total surface area of a 5-cm cube.
One side = 5X5 = 25 cm2
25 X 6 = 150 cm2
What percentage of 50 km is 10 m? Leave your answer in decimal.
50 km = 50 000 m
10/50 000 X 100% = 0.02%
What is the perimeter of a quadrant with radius of 21cm? Use 22/7 as PI.
(22/7 X 42) + 21 + 21 = 174 cm
Cindy cycles between her home and school from Monday to Friday, at a speed of 15 km/h. The school is 5 km away from her house. How long did Cindy cycle each week? Leave your answer in hour and min.
T = 5/15 = 1/3 h = 20 min
20 min X 2 (To and fro) = 40min
40min X 5 = 200 min = 3 h 20 min
A sack of potatoes is 3kg.
1/2 of it was used to make potato chips and 5/6 kg was used to cook curry. How many kilograms of potatoes was left?
1/2 of 3kg = 1 1/2 kg
3/2 - 5/6 = 9/6 - 5/6
= 4/6
= 2/3 kg
Simplify 20 - 5a + 9 X 2 + 8a
20 - 5a + 9 X 2 + 8a
= 20 - 5a + 18 + 8a
= 38 + 8a - 5a
= 38 + 3a
Express 12.5% as a decimal. Leave your answer in 2 decimal places.
12.5/100 = 0.125 = 0.13 (2 d.p.)
A small circle of diameter 20cm is cut out from the center of a bigger circle of diameter 30cm. Find the area and perimeter of the remaining figure. Leave your answers in terms of PI.
(15 X 15 X PI) - (10 X 10 X PI) = 125 PI cm2 (Area)
(PI X 30) + (PI X 20) = 50 PI cm (Perimeter)
Tommy jogs at a speed of 15m/s in 8s. His sister jogs the same distance in 12s. Find the speed of his sister.
D = 15 X 8 = 120 m
Sister's speed = 120 / 12 = 10 m/s
Marc paints a house in 4 days. Ken paints a house in 6 days. If they work together, how long does it take to paint the house?
Marc Ken
4 days --> 1 house 6 days --> 1 house
1 day --> 1/4 house 1 day --> 1/6 house
1/4 + 1/6 = 5/12 (in 1 day)
12/5 = 2.4 days to paint the house
Find the area of a triangle with a base of 20 cm and a height of 8z cm, given z = 2.
8z = 8 X 2 = 16
1/2 X 20 X 16 = 160 cm2
25% of James' savings is equal to 20% of Tom's savings. Express the ratio of James's savings to Tom's savings.
James : Tom
25/100 : 20/100
1/4 : 1/5
4 : 5
A quadrant has the same area as a circle with radius of 7cm. Find the radius of the quadrant. Use 22/7 as PI.
Area of circle = 22/7 X 7 X 7 = 154 cm2
1/4 X 22/7 X r X r = 154
r X r = (154 X 28) / 22 = 196
r = 14 cm
Mr. Alan drove at a speed of 70km/h for half hour. He increased his speed by 10km/h and drove for another 45 min. Find the average speed of his entire journey.
D1 = 70/2 = 35km
D2 = 80 X 45/60 = 60km
1/2 h + 3/4 h = 5/4 h
Average speed = 95 divides 5/4 = 76 km/h
2/3 of Cindy's cards is equal to 1/4 of Marc's cards. If Marc has 20 more cards than Cindy, how many cards does Cindy have?
2/3 = 1/4
2/3 = 2/8 Cindy = 3U Marc = 8U
5U = 20
1U = 4
3U = 12 cards for Cindy
How much more water can be added to a tank with a 10-cm square base and a height of 18 cm when it is half-filled with water? Leave your answer in litres.
1/2 X 18cm = 9cm (half of the height)
10 X 10 X 9 = 900 cm3 = 0.9 litres
There are 45 boys and 30 more girls than boys, with another 360 adults in a room. What percentage of the people are children?
Girls = 45 + 30 = 75
Children = 45 + 75 = 120
People = 120 + 360 = 480
120/480 X 100% = 25%