Nexus Tech is a software company that employs 180 developers across three departments: Design, Engineering, and Marketing. The developers are also classified by their experience level as either Junior or Senior.
The distribution of the developers is shown in the table below:
| Experience Level | Design | Engineering | Marketing |
|---|---|---|---|
| Junior | 25 | 70 | 35 |
| Senior | 15 | 20 | 15 |
A developer is selected at random. Find the probability that: (i) the developer is a Junior. (ii) the developer works in the Engineering department.
Given that a randomly chosen developer is Senior, find the probability that this developer does not work in the Design department.
The HR director wants to select three different developers at random to form a focus group. Calculate the probability that all three chosen developers work in the Engineering department.
200 exam-style questions on OCR A Level Maths 2.3 Probability, covering 2.3.1 Mutually exclusive and independent events, 2.3.2 Diagrams to assist probability calculations, 2.3.3 Conditional probability (A-level only), 2.3.4 Conditional probability from first principles (A-level only), and 2.3.5 Modelling with probability. Each one has a worked solution and a mark scheme showing where the marks go.