This page explores finding a missing number in a set when given the mean value and other numbers in the set. The problem demonstrates understanding of averages and numerical relationships.

Vocabulary: Mean is the average of a set of numbers, calculated by dividing the sum by the count of numbers.

Example: With four known numbers (13, 12, 9, 16) and a mean of 12, the fifth number can be found by: (12 × 5) - $13 + 12 + 9 + 16$ = 10

Highlight: The solution involves working backwards from the desired mean to find the missing value.

This page covers two distinct problems: calculating the empty weight of a chocolate box and determining distance traveled by a tortoise.

Example: For the chocolate box:

• Initial weight: 290g with 7 chocolates
• After eating 3 chocolates: 194g
• Empty box weight: 32g

Highlight: The tortoise problem involves converting time and distance measurements, showing that in 2 hours (8 × 15-minute intervals), the tortoise walks 13.6km.

Definition: Rate of travel is the distance covered in a given time period, used to calculate total distance over longer durations.

This page focuses on calculating the area of a square using information about an equilateral triangle. The problem demonstrates the relationship between perimeter and area in geometric shapes.

Definition: Perimeter is the total distance around a shape, while area is the space inside the shape.

Example: When the perimeter of an equilateral triangle is 36cm (12cm + 12cm + 12cm), and it equals the square's perimeter, each side of the square must be 9cm (36cm ÷ 4).

Highlight: The area of the square is calculated by multiplying the length by width: 9cm × 9cm = 81cm².