A bus company sells adult tickets and child tickets for a day trip. A child ticket costs £1.30 less than an adult ticket. A family group of 4 adults and 6 c...

Assessment: Mathematics Specification B 4MB1 | Paper 2 Mock 01 | Written Paper 2 Subject: Mathematics Specification B - 4MB1

Question 1 Report

A bus company sells adult tickets and child tickets for a day trip. A child ticket costs £1.30 less than an adult ticket. A family group of 4 adults and 6 children pays £37.20 in total. The cost of one adult ticket is \(a\) pounds.

  1. Write down an equation in \(a\). (2)
  2. Solve your equation to find the cost of an adult ticket. (2)
  3. Work out the total cost for 3 adults and 5 children. (2)

Answer Details

Two ticket prices are linked by a fixed difference, so both can be written using a single letter. That is what keeps this to one equation rather than a pair of simultaneous equations.

(a) Equation in \(a\). [2]
An adult ticket costs \(a\) pounds, and a child ticket costs £1.30 less, so it costs \((a - 1.30)\) pounds. The group buys 4 adult and 6 child tickets for £37.20:

\[4a + 6(a - 1.30) = 37.20\]

One mark for the child ticket expression, one for the complete equation. The bracket is essential: all six child tickets are reduced by £1.30 each, not £1.30 in total.

(b) Cost of an adult ticket. [2]
Expand and collect:

\[4a + 6a - 7.80 = 37.20\] \[10a = 37.20 + 7.80 = 45 \quad\Rightarrow\quad a = 4.50\]

An adult ticket costs £4.50. Check: a child ticket is \(4.50 - 1.30 = 3.20\) pounds, and \(4 \times 4.50 + 6 \times 3.20 = 18.00 + 19.20 = 37.20\) pounds, as stated.

(c) Cost for 3 adults and 5 children. [2]
Using £4.50 and £3.20:

\[3 \times 4.50 + 5 \times 3.20 = 13.50 + 16.00 = 29.50\]

The total is £29.50. One mark for the child price, one for the total. Write money answers to two decimal places, so £29.5 should be given as £29.50.

Examination point: when one quantity is described in terms of another, name only the one you are told to name and build the second from it. Introducing a second letter here would leave you with one equation and two unknowns.

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