The mean of 15 values is 42.
Two further values, 60 and 66, are then included, and one of the original values, 30, is removed.
Find the mean of the 16 values that remain.
State, with a reason, the effect of these changes on the standard deviation.
39 exam-style questions on AQA A Level Maths 2.2.3 Central tendency, variation and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.