WASSCE Core Mathematics · Paper 1 style

Mensuration

One sample question with the full working. 26 more in the app, with instant feedback and repair sessions for the traps below.

Find the area of a circle of radius 7 cm. (Take π = 22/7)

Show the answer and working

Answer: B

A = πr² = 22/7 × 7 × 7 = 22 × 7 = 154 cm².

Trap A Confuses area and perimeter: Perimeter/circumference = length around (cm). Area = space inside (cm²). Check the units the question expects.

Trap C Confuses area and perimeter: Perimeter/circumference = length around (cm). Area = space inside (cm²). Check the units the question expects.

Trap D Mixes up radius and diameter: Radius is HALF the diameter. A = πr²; C = 2πr = πd. Write r = ? before substituting.

Confuses area and perimeter
Perimeter/circumference = length around (cm). Area = space inside (cm²). Check the units the question expects.
Mixes up radius and diameter
Radius is HALF the diameter. A = πr²; C = 2πr = πd. Write r = ? before substituting.
Uses only part of the information
Tick off every number and every condition in the stem as you use it. If one is unticked at the end, the answer is incomplete.
Calculates a different quantity
Name the quantity and its unit before you start (remainder; horizontal distance; cm²). After calculating, check your number is that quantity and not a neighbour.
Applies the rule for a different situation
Identify the situation first (angle at centre? opposite angles of a cyclic quadrilateral? reverse bearing?) and write the rule that belongs to it before calculating.
Forgets the fractional factor in solid volumes
A cone fills exactly ⅓ of the cylinder with the same base and height: V = ⅓πr²h. Sphere: V = 4/3 πr³. Learn formulas with their fractions.
Leaves out a term of the formula
Write the full formula before substituting and tick each term as you fill it in.
Writes an amount with the wrong unit
A percentage is a ratio × 100. An amount in cedis only becomes a % after dividing by the original amount.