How can you use bar diagrams to compare quantities in real-world situations

Ineeeeed this is due tomorrow and i dont know the answer can you find all the exponents

How do you solve a question like this?

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 .