The bar graph below shows the range of marks scored by a group of students in a Maths test. What fraction of the pupils obtained at least 45 marks in the test? Give your answer in the simplest form.

1. Read the number of students in each mark range from the bar graph and find the total number of students

Number of students in each range:

• $0-44$: $10$
• $45-74$: $25$
• $75-84$: $45$
• $85-100$: $20$

Total number of students $= 10 + 25 + 45 + 20 = 100$

2. Find the number of students who obtained at least 45 marks

Students with at least $45$ marks are those in the ranges $45-74$, $75-84$, and $85-100$.
Number of students $= 25 + 45 + 20 = 90$
Alternatively, using the total: $100 - 10 = 90$

3. Express the number of students as a fraction of the total and simplify

Fraction $= \frac{90}{100} = \frac{9}{10}$