QR formulas

Question 1

Mean

Answer 1

Average. Add up all the values and divide the total by how many there are

Question 2

Median

Answer 2

Middle number of a set of data.

Order numerically (lowest to highest)

Question 3

Mode

Answer 3

Number that occurs most often in a set

Question 4

Range

Answer 4

Difference between highest and lowest

Question 5

Rate problems (think of it like speed = distance/time. E.g., might have running tap, etc.) and relative speed.

Answer 5

When 2 things travel towards each other, we need to add the 2 velocities together .
E.g. Train 1 going east 50mph and train going west 40mph. They are 135 miles apart. How long before they collide?
t = 135miles/(40mph+50mph) = 135/90 = 1.5 hours.

When 2 things travel alongiside each other -take away their velocites together.

Question 6

Compound and simple interest formula

Answer 6

Simple: I = P * T * R; Compound: I = P(1+r/n)^nt

Question 7

Tax problems

Answer 7

Usually skip - time consuming, but always figure out what bracket you’re in. May involve algebra. Don’t do if too complex. Then layer/collate the tax. E.g $,65, 000 income: In this bracket, so do the brackets below that, then calculate every dollar in that particular bracket.

Question 8

Dice problems

Answer 8

Rolling 2 dice - Total no. of permutations = 36
E.g. What is the probability of rolling 2 dice and having the 2 numbers add up to 4?
Three possibilities - 2+2, 1+3, 3+1
- (1/6 * 1/6) x 3

Therefore probability - 3/36 = 1/12

Question 9

Deck of cards

Answer 9

Total number of cards = 52 (Without jokers)
4 Suits (Heart, club, spade, diamond)
13 cards per suit
With replacement: Total number of cards must go back to 52 and cards of interest must go back to initial amount.
Without replacement: Must decrease total number of cards by 1 and decrease number of cards of interest by 1.
E.g. Probability of pulling 3 spades in a deck without replacement?
13/52 * 12/51 * 11/50 = 33/2550

Question 10

Acceleration formula

Answer 10

Acceleration = Change in velocity/tim

Question 11

Area of a circle

Answer 11

πr^2 r=radius

Question 12

Circumference of a circle

Answer 12

2πr

Question 13

Area of a triangle

Answer 13

1/2 * base * height

Question 14

Sphere Volume

Answer 14

(4/3)πr^3

Question 15

Volume of a cylinder

Answer 15

πr^2 * h

Question 16

Surface Area of Cylinder

Answer 16

2πrh+2πr^2 (round bit + 2 circles)

Question 17

1/20

Answer 17

0.05 = 5%

Question 18

1/10

Answer 18

0.1 = 10%

Question 19

1/9

Answer 19

0.11 = 11%

Question 20

1/8

Answer 20

0.125 = 12.5%

Question 21

1/7

Answer 21

0.14 = 14%

Question 22

1/6

Answer 22

0.17 = 17%

Question 23

1/5

Answer 23

0.2 = 20%

Question 24

1/4

Answer 24

0.25 = 25%

Question 25

1/3

Answer 25

0.33 = 33%

Question 26

1/2

Answer 26

0.5 = 50%

Question 27

Percentage Change formula

Answer 27

(Final-Initial)/Initial * 100

Question 28

Milli (could be gram, milimetre, etc.) CONVERTING FROM LARGER TO SMALLER (E.g. Meter to milimeter) = multiply. Smaller to larger = divide.

Answer 28

0.001 mg e.g. 1g = 1 * 1000 or 1/0.001 = 1000mg

gives you mg in 1 g.

Question 29

Centi (general)

Answer 29

0.01 e.g. 1m = 1 * 100 or 1/0.01 = 100cm

Question 30

Deci

Answer 30

0.1. So one deci metre is 1/10 of meter. Or it is 10cm.

Question 31

Kilo

Answer 31

1000. Times and divide by 1000 (e.g kg to g)

Question 32

Mega

Answer 32

1 Million (1,000,000). Times and divide by 1 mil. (e.g. megametre to metre).

Question 33

Giga

Answer 33

Billion (1,000,000,000). (e.g. gigametre to metre). Subtract digits for larger units (e.g. gigameter to mega meter - divide by [taking 6 zerois) 1000]

Question 34

Temperature °C to °F

Answer 34

(°C × 9/5) + 32 = F

Question 35

1 inch in cm

Answer 35

2.54 cm (Estimate - 2.5cm)

Question 36

1 mile in ft and km

Answer 36

5280 ft = 1.6km (Estimate - 5000ft and 1.5km).

Question 37

1 ft in inches

Answer 37

12 in

Question 38

1cm in mm and inches

Answer 38

10mm = 0.4in

Question 39

1kg in g and lb

Answer 39

1000g = 2.2lb

Question 40

1lb in g and ounces

Answer 40

454g = 16 ounces

Question 41

1 tonne in kg and g

Answer 41

1000kg = 100,000g

Question 42

1m^3 in litres

Answer 42

1000l

Question 43

Area - 1m^2 in cm

Answer 43

10,000cm

Question 44

Area - 1km^2 in cm

Answer 44

1,000,000m

Question 45

Q
Time - Weeks and days in year

Answer 45

52 weeks, 365 days in a year

Question 46

Hrs to mins to secs

Answer 46

Hrs 🠒 *60 - Mins 🠒 *60 - Secs

Question 47

Secs to mins to hrs

Answer 47

Secs 🠒 /60 - Mins 🠒 /60 - Hrs