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Nov 2016 p61 q4
3224
Packets of rice are filled by a machine and have weights which are normally distributed with mean 1.04 kg and standard deviation 0.017 kg.
Find the probability that a randomly chosen packet weighs less than 1 kg.
How many packets of rice, on average, would the machine fill from 1000 kg of rice?
The factory manager wants to produce more packets of rice. He changes the settings on the machine so that the standard deviation is the same but the mean is reduced to \(\mu\) kg. With this mean the probability that a packet weighs less than 1 kg is 0.0388.
Find the value of \(\mu\).
How many packets of rice, on average, would the machine now fill from 1000 kg of rice?
Solution
(i) To find the probability that a randomly chosen packet weighs less than 1 kg, we standardize the variable: