Percentages, profit and loss and discounts
A notebook costs 100 baht. It is discounted by 10%.
How much is the discount? What is the new price?
Discount: ten baht
New price: 90 baht
A rectangle has a length of 8 m and a width of 5 m.
Find the perimeter.
P=8+5+8+5=26m
Name the quadrilateral that has:
4 equal sides
4 right angles
square
How many right angles are in a straight line?
2
Out of 10 marbles, 3 are red.
What is the probability of choosing a red marble?
3/10=30/100=0.30=30%
A toy costs 200 baht. It has a 25% discount.
Is it cheaper than a toy costing 180 baht with a 10% discount? Explain.
New price toy one: 150 baht
New price toy 2: 162 baht
Yes it is cheaper by: 162-150=12 baht
A square has a perimeter of 24 cm.
What is the length of one side? What is its area?
P=24cm, a square has 4 sides the same length.
side=P/4=24/4=6cm
Which shape has one pair of parallel sides only?
trapezium/trapeziod
Two lines never meet and are always the same distance apart.
What are they called?
parallel lines
You roll a normal dice.
Is it more likely to roll an even number or a 6? Why?
even number because there are 3 even numbers but only one 6.
A shop buys a football for 120 baht and sells it for 150 baht.
a) Is this a profit or loss?
b) How much?
c) What percentage profit is this?
a) profit
b) 30 baht
c) (30/120)*100=25%
A parallelogram has a base of 10cm and a height of 6 cm.
The slanted side is 8 cm.
Find:
a) the area
b) the perimeter
a) area=base x height=10x6=60cm^2
b) perimeter=10+10+8+8=36cm
A shape has:
opposite sides equal
opposite sides parallel
no right angles
What shape is it? Explain one property.
parallelogram/rhombus
A rhombus has equal sides.
How many right angles does it usually have?
0
A bag has 2 red, 4 blue, and 6 green counters.
What is the probability of choosing a counter that is not red?
10/12=5/6
A shirt costs 300 baht.
First, it is discounted by 20%.
Then, there is an extra discount of 10% on the new price.
What is the final price?
20% of 300= 60, 300-60=240
10% of 240=24, 240-24=216
Two shapes have the same area of 48 cm².
Shape A: rectangle
Shape B: parallelogram
Can they have different perimeters? Explain why or why not.
Yes. In a parallelogram the height is different from the length of the slanted lines.
A shape has four equal sides but no right angles.
Some students say it is a square.
Are they correct? Why or why not?
not correct because a square has 4 right angles.
the correct answer is rhombus.
Line A is perpendicular to line B.
Line B is perpendicular to line C.
What can you say about lines A and C? Explain.
line A and C are parallel
Two bags:
Bag A: 1 red, 9 blue
Bag B: 4 red, 6 blue
Which bag gives you a better chance of picking red? Explain.
Bag a: 1/10=0.1=10%
Bag B: 4/10=2/5=40/100=40%
ans: B
Two shops sell the same bag.
Shop A: 400 baht with 25% off
Shop B: 320 baht with 10% off
Which is cheaper? Prove it with calculations.
Shop A: discount=100 baht, 400-100=300 baht
Shop B: discount=32 baht, 320-32=288 baht
Shop B is cheaper by 300-288=12 baht
A garden is 12 m long and 8 m wide.
A fence goes all the way around it.
Fencing costs 90 baht per metre, but there is a 10% discount.
What is the total cost of the fence?
fencing costs: 81 baht per metre. (90-9)
perimeter: 12+12+8+8=40m
40 x 81= 3240 baht
Which quadrilateral fits all these clues?
Two pairs of adjacent equal sides
One pair of equal opposite angles
No parallel sides
Explain how you know.
Line m is perpendicular to line n.
A ray makes a 35° angle with line m.
What is the angle between the ray and line n?
Explain your reasoning.
55 degrees
A bag contains:
3 red counters
5 blue counters
2 green counters
You are allowed to add counters only (you cannot remove any).
What is the smallest number of counters you must add to make the game fair?
How many of each colour will there be at the end?
add 2 red and 3 green. Therefore add 5 counters.
5 of each colour