The storage life of a specialized organic catalyst, CCC days, is modeled by a normal distribution with a mean of 45 days and a standard deviation of 8 days.
Calculate the probability that a randomly selected batch of this catalyst lasts longer than 60.0 days.
A 'warning threshold' is set at ddd days, such that the probability of a catalyst failing before this threshold is 0.08. Determine the value of ddd.
A laboratory process requires the catalyst to remain effective for a further 5 days. Given that a specific batch of catalyst has already been stored for 60 days and is still effective, find the probability that it will last until the process is finished.
616 exam-style questions on Edexcel A Level Maths The Normal Distribution, covering 3.1 The Normal Distribution, 3.2 Finding Probabilities for Normal Distributions, 3.3 The Inverse Normal Distribution Function, 3.4 The Standard Normal Distribution, 3.5 Finding the mean and standard deviation, 3.6 Approximating a Binomial Distribution, and 3.7 Hypothesis Testing with the Normal Distribution. Each one has a worked solution and a mark scheme showing where the marks go.