A high-precision voltage regulator is tested for drift during calibration. In each micro-adjustment step, the voltage deviation VVV is an integer millivolt value where V∈{−3,−1,1,3}V \in \{-3, -1, 1, 3\}V∈{−3,−1,1,3}, with each value being equally likely.
Determine the mean and the variance of VVV.
A sequence of 150 independent micro-adjustments is performed. Using the Central Limit Theorem, calculate an approximation for the probability that the average voltage deviation of these 150 adjustments is less than -0.25.
351 exam-style questions on AQA A Level Maths 2.4.2 The Normal distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.