For every 4 girls in Mr Hegarty's class there are 5 boys. What is the ratio of boys to girls in the class? Give your answer in its simplest form.

An energy drink company claims that its product increases students' memory levels. to support its claims, the company issues advertisements claiming that 8 out of 10 people (chosen randomly from across the country) who tried their product reported improved memory. the missing component in this study is a .