Algebra related
Number related
Percentages
Logical Puzzles
Upper and Lower bounds
100
Simplify (-x*2y*2)(xy*2)
-x*3y*4
100
What 3 positive numbers give the same results when × and + ?
1,2,3
100
Decrease $580 by 15%
= 580 x 0.85 $493
100
A milkman has 2 empty jugs: a 3 gallon jug and a 5 gallon jug. How can he measure exactly 1 gallon without wasting any milk?
He first use the 3 gallon jug to fill the 5 gallon jug. Then use the 3 gallon jug to once again fill the 5 gallon jug until it's full. The remaining in the 3 gallon jug was precisely 1 gallon.
100
A garden is 9m long to the nearest m. What is the shortest the garden could be ?
8.5m
200
Simplify 4xy^4 × 2xy + x^2y^5
9x^2y^5
200
How do you get 24 from 9, 6, 11 and 3 using adding, subtracting, multiplying, division
(6-3) x 11 - 9 = 24
200
The boss gives all his employees a 2% rise. Pal use to earn $6 an hour. How much does he earn after the rise?
$6.12 per hour
200
Ten red socks and ten blue socks are all mixed up in a dresser drawer. The 20 socks are exactly alike except for their colour. The room is in pitch darkness and you want two matching socks. What is the smallest number of socks you must take out of the drawer in order to be certain that you have a pair that match?
Three socks
200
Mr Adams has to drive 120km for a conference, to the nearest 10km. What is the shortest Mr Adams' journey could be ?
115 km
300
The height h of water in a cylindrical container with radius is 5 cm is equal to 10 cm. Peter needs to measure the volume of a stone with a complicated shape and so he puts the stone inside the container with water. The height of the water inside the container rises to 13.2 cm. What is the volume of the stone in cubic cm?
80 pi cm^3
300
Replace ? with +-×÷ 18 ? 12 ? 4 ? 5 = 59
18 × 12 ÷ 4 + 5
300
Suppose the price of an item increases by 19%, and then decreases by 30%. Was it an increase or decrease? What is the percentage change?
Decrease of 16.7%
300
A cat lies every Monday, Tuesday and Wednesday and the other days he speaks the truth. A dog lies on Thursdays, Fridays and Saturdays and the other days of the week he speak the truth. Cat: Yesterday, I was lying Dog: So was I Which day did they say that?
Thursday
300
The numbers has been rounded to 2 d.p. Work out the biggest possible answer when 7.74 - 3.74 ?
=7.745 - 3.735 = 4.01
400
Factorize y^2-4y-8=5y+28
(y+3)(y-12)=0
400
To get the answer 24 by using the numbers 7,3,7,3 (use +-×÷)
= 7 x ((3 + 7) +3)
400
The price increases by 20%, and then decreases by 70%. What is the resulting percent increase or decrease?
Decrease of 64%
400
At a party, everyone shook hand with everybody else. There was 66 handshakes. How many people were at the party?
The answer is 12 - 1+2+3... +n = 66 - n(n+1)/2=66 -Factorising n^2+n-132=0 - Answer = 11
400
The numbers has been rounded to 2 d.p. Work out the smallest possible answer when 3.38 is divided by 9.38 ? Round to 3 significant figures.
= 3.375 / 9.385 = 0.360
500
The average age of 10 members of a committee is the same as 4 years ago because an old member has been replace. How much younger is the new member?
Sum of nine member =x and the age of old one=z its average 4 yrs before=(x+z)/10 after 4 yrs let z be replaced by y avg=(x+4×10+y)/10 =(x+z)/10=(x+40+y)/10 z=y+40 40 years
500
To get the answer 24 by using the numbers 8,8,3,3 (use +-×÷)
8 ⁄ (3 − ( 8/3 ))
500
Suppose the price of an item increases by 50%, and then decreases by 50%. What is the resulting percent increase or decrease?
Decrease of 25%
500
The emperor offers you a chance to live. He gives you 50 black marbles and 50 white marbles and 2 empty bowls. He says,'divide these 100 marbles into these two bowls however you like. Then I will blindfold you and mix the bowls around. You can choose one bowl and pick one marble. If it's white you live, but if it's black you die.' How will you divide the marbles?
Place 1 marble in one bowl and the rest in another bowl (49 white and 50 black) This way you begin with a 50/50 chance of choosing the bowl with just one white marble. But even if you choose the other, you still have almost a 50/50 to picking a white marble.
500
A hoist can lift 1,600 kg, given to 2 significant figures. It is being used to load boxes that weigh 48 kg to the nearest kg. How many boxes can the hoist safely lift?
1550 ÷ 48.5 = 31.9…. The hoist can lift 31 boxes safely
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