4 A company sells small and large bags of rice. The masses of the small bags of rice are normally distributed with mean 1.20 kg and standard deviation 0.16 kg .
- In a random sample of 500 of these small bags of rice, how many would you expect to have a mass greater than 1.26 kg ?
The masses of the large bags of rice are normally distributed with mean 2.50 kg and standard deviation \(\sigma \mathrm { kg } .20 \%\) of these large bags of rice have a mass less than 2.40 kg . - Find the value of \(\sigma\).
A random sample of 80 large bags of rice is chosen. - Use a suitable approximation to find the probability that fewer than 22 of these large bags of rice have a mass less than 2.40 kg .