The masses of a certain species of animal are known to be normally distributed with standard deviation σkg. A researcher obtains the masses of a random sample of n animals of this species and uses these masses to find two confidence intervals (α% and 90%) for the population mean. The width of the α% confidence interval is 1.414 × the width of the 90% confidence interval.

A selection of 3 letters from the 8 letters of the word COLLIDER is made.

Last Saturday, Sarah recorded the colour and type of 160 cars in a car park. All the cars that were not red or silver...

The discrete random variable X has the following probability distribution. X|-2|0|1|3|4 P(X = x)|0.2|0.1|p|0.1|q

The variables x and y satisfy the equation yⁿ = Ax³, where n and A are constants. It is given that y = 2.58 when x = ...

The parametric equations of a curve are x = 2t + sin 2t, y = 1 – 2 cos 2t, for −½π < t < ½π.

The variables x and θ satisfy the differential equation x cos² θ (dx/dθ) = 2 tan θ + 1, for 0 ≤ θ < ½π and x > 0. It ...