# Using Simple Formulae (1)

In this worksheet, students use simple formulae to answer questions. Symbols are used. Key stage:  KS 2

Curriculum topic:   Maths and Numerical Reasoning

Curriculum subtopic:   Equations and Algebra

Difficulty level:   ### QUESTION 1 of 10

A formula tells you how to work something out based on what you know already.

If you know the length of the side of a square, how would you work out its perimeter?

The answer is to multiply it by 4, because a square has 4 sides of equal length.

We can use a formula to state this, but first we must say what the letters stand for.

s = side length of square

P = perimeter of square

The formula will be

P = 4s

which means P = 4 × s.

If s = 5,

P = 4 × 5 = 20.

If s = 15,

P = 4 × 15 = 60.

Example

Mum uses the following formula to work out our pocket money.

P = A × 30 + 100

where P stands for pocket money in pence and A stands for our age in years.

Bill is 5 years old. How much does he get?

Amy is 15 years old. How much does she get?

Bill

A = 5

P = 5 × 30 + 100 = 150 + 100 = 250 pence

Amy

A = 15

P = 15 × 30 + 100 = 450 + 100 = 550 pence

The formula for the perimeter of a square is

P = 4 × s

where:

P = Perimeter

s = side length of square.

Use the formula to work out the perimeter when the side length = 8.

The formula for the perimeter of a square is

P = 4 × s

where:

P = Perimeter

s = side length of square.

Use the formula to work out the perimeter when the side length = 12.

Mum uses the following formula to work out the pocket money she gives to her children.

P = A × 30 + 100

where P stands for pocket money in pence and A stands for the child's age in years.

Bill is 6 years old. How much does he get in pence?

(Just write the number.)

Mum uses the following formula to work out the pocket money she gives to her children.

P = A × 30 + 100

where P stands for pocket money in pence and A stands for the child's age in years.

Kate is 12 years old. How much does she get in pence?

(Just write the number.)

Amy uses the following formula to work out a number, which she calls A, when she knows the number B.

A = B + 25

What is A, when B = 5?

Amy uses the following formula to work out a number, which she calls A, when she knows the number B.

A = B ÷ 5

What is A, when B = 25?

Amy uses the following formula to work out a number, which she calls A, when she knows the number B.

A = B - 5

What is A, when B = 5?

Chef uses this formula to work out the cooking time for a chicken:

T = W × 15 + 60

where T is the time in minutes and W is the weight of the chicken in pounds.

For how many minutes should he cook a 4-pound chicken?

(Just write the number.)

Chef uses this formula to work out the cooking time for a chicken:

T = W × 15 + 60

where T is the time in minutes and W is the weight of the chicken in pounds.

For how many minutes should he cook a 6-pound chicken?

(Just write the number.)

Chef uses this formula to work out the cooking time for a turkey:

T = W × 15 + 60

where T is the time in minutes and W is the weight of the turkey in pounds.

For how many minutes should he cook a 10-pound turkey?

(Just write the number.)

• Question 1

The formula for the perimeter of a square is

P = 4 × s

where:

P = Perimeter

s = side length of square.

Use the formula to work out the perimeter when the side length = 8.

32
EDDIE SAYS
P = 4 × 8 = 32
• Question 2

The formula for the perimeter of a square is

P = 4 × s

where:

P = Perimeter

s = side length of square.

Use the formula to work out the perimeter when the side length = 12.

48
EDDIE SAYS
P = 4 × 12 = 48
• Question 3

Mum uses the following formula to work out the pocket money she gives to her children.

P = A × 30 + 100

where P stands for pocket money in pence and A stands for the child's age in years.

Bill is 6 years old. How much does he get in pence?

(Just write the number.)

280
EDDIE SAYS
P = 6 × 30 + 100 = 180 + 100 = 280 pence
• Question 4

Mum uses the following formula to work out the pocket money she gives to her children.

P = A × 30 + 100

where P stands for pocket money in pence and A stands for the child's age in years.

Kate is 12 years old. How much does she get in pence?

(Just write the number.)

460
EDDIE SAYS
P = 12 × 30 + 100 = 360 + 100 = 460 pence
• Question 5

Amy uses the following formula to work out a number, which she calls A, when she knows the number B.

A = B + 25

What is A, when B = 5?

30
EDDIE SAYS
A = 5 + 25 = 30
• Question 6

Amy uses the following formula to work out a number, which she calls A, when she knows the number B.

A = B ÷ 5

What is A, when B = 25?

5
EDDIE SAYS
A = 25 ÷ 5 = 5
• Question 7

Amy uses the following formula to work out a number, which she calls A, when she knows the number B.

A = B - 5

What is A, when B = 5?

0
EDDIE SAYS
A = 5 - 5 = 0
• Question 8

Chef uses this formula to work out the cooking time for a chicken:

T = W × 15 + 60

where T is the time in minutes and W is the weight of the chicken in pounds.

For how many minutes should he cook a 4-pound chicken?

(Just write the number.)

120
EDDIE SAYS
W = 4
T = 4 × 15 + 60 = 60 + 60 = 120 minutes
• Question 9

Chef uses this formula to work out the cooking time for a chicken:

T = W × 15 + 60

where T is the time in minutes and W is the weight of the chicken in pounds.

For how many minutes should he cook a 6-pound chicken?

(Just write the number.)

150
EDDIE SAYS
W = 6
T = 6 × 15 + 60 = 90 + 60 = 150 minutes
• Question 10

Chef uses this formula to work out the cooking time for a turkey:

T = W × 15 + 60

where T is the time in minutes and W is the weight of the turkey in pounds.

For how many minutes should he cook a 10-pound turkey?

(Just write the number.)

210
EDDIE SAYS
W = 10
T = 10 × 15 + 60 = 150 + 60 = 210 minutes
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