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When do I use it and how do I use the past perfect?

The past perfect is used to describe a past action that happened before another past action.It expresses the anteriority of a past action, compared to another past action expressed by the simple past, t...

Answered by • French tutor

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A medical test will be positive for 0.05% of people and negative for everyone else. Suppose a hospital will test 4000 patients each day. Use an appropriate approximation to find the probability that 5 people test positive tomorrow. (5SF)

Note that we have a constant probability, fixed number of tests, independent patients and only two outcomes, so we can write a binomial distribution X~Bin(4000,0.0005) where X is the random variable repre...

Answered by John M. • Maths tutor

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Differentiate 2cos(x)sin(x) with respect to x

To solve this differential, firstly note that 2cos(x)sin(x) = sin(2x) (by the Double-Angle Sine Identity), this makes computing the differential a lot easier. To differentiate sin(2x) we need to use the c...

Answered by Ryan H. • Maths tutor

7505 Views

How do I know when to choose which statistical test?

MOID - Mann Whitney U test; ordinal data, independent groups, test of DifferenceSCOR - Spearmans test; test of Correlation, ordinal data, repeated measures or matched pairs designCIND - Chi squared test; ...

Answered by • Psychology tutor

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Consider the function f(x) = 2/3 x^3 + bx^2 + 2x + 3, where b is some undetermined coefficient:

a) Find f ' (x) and f ''(x). f' = 2x² + 2bx + 2f'' = 4x + 2bb) You are given that f(x) has a stationary point at x = 2. Use this information to find b.2x² + 2bx + 2, x=2Stationary po...

Answered by Charlie P. • Maths tutor

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