For her birthday, Rachael went to Belfast with her family - Junior Cycle Mathematics - Question 4 - 2015

To convert the hotel room cost from sterling to euro, we use the exchange rate:

Cost in sterling: £140 Exchange rate: £1 = €1.28.

Calculation:

$140 imes 1.28 = €179.20$

Thus, the cost of the hotel room is €179.20.

To find the percentage of a child's ticket cost relative to an adult's ticket, we set up the formula:

Cost of a child's ticket: €60 Cost of an adult's ticket: €80.

Calculation:

rac{60}{80} imes 100 = 75 ext{%}

Therefore, the cost of a child's ticket is 75% of the cost of an adult's ticket.

Given the total number of people at the concert is 4000 and the ratio of children to adults is 3:5, we can express the numbers of children and adults as follows:

Let the number of children be 3x and adults be 5x. Thus, the equation is:

$3x + 5x = 4000$

Simplifying gives:

$8x = 4000$

Now, solving for x:

x = rac{4000}{8} = 500

Now, calculate the number of children:

$3x = 3 imes 500 = 1500$

Therefore, the number of children at the concert is 1500.