To find out how many Year 10 girls there are in the school, you can follow these steps:
Calculate the number of Year 10 pupils: 20% of 1600 pupils.
Year 10 pupils = 0.20 * 1600 = 320 pupils
Calculate the number of Year 10 girls: 45% of the Year 10 pupils.
Year 10 girls = 0.45 * 320 pupils = 144 girls
So, there are 144 Year 10 girls in the school