This is a probability problem without replacement.
First, let's find the total number of ways Amaan can pick two notes.
There are 4 choices for the first note.
After picking one, there are 3 choices left for the second note.
Total number of ordered pairs (outcomes) = 4 × 3 = 12.
Next, let's find the number of pairs where the sum is at least £30 (i.e., £30 or more). We can list them systematically:
- (£5, £10) = £15 (No)
- (£5, £20) = £25 (No)
- (£5, £50) = £55 (Yes)
- (£10, £5) = £15 (No)
- (£10, £20) = £30 (Yes)
- (£10, £50) = £60 (Yes)
- (£20, £5) = £25 (No)
- (£20, £10) = £30 (Yes)
- (£20, £50) = £70 (Yes)
- (£50, £5) = £55 (Yes)
- (£50, £10) = £60 (Yes)
- (£50, £20) = £70 (Yes)
Counting the "Yes" outcomes, we have 8 favourable outcomes.
The probability is the number of favourable outcomes divided by the total number of outcomes.
P(sum ≥ £30) = 8 / 12
This fraction can be simplified by dividing the numerator and denominator by their greatest common divisor, which is 4.
P(sum ≥ £30) = 2 / 3.