4b) Work out the mean and standard deviation of the following: picture included Note: I ended up with the simultaneous equations, which are correct according to the markscheme BUT the answers I got upon solving them were incorrect.
μ = 170 + 1.6449σ
μ = 180 - 0.8416σ

What I got after solving these were:
μ = 169.5306859
σ = 12.44864932

But according to the markscheme, I should have gotten:
μ = 176.615...
σ = 4.021...

Can someone explain to me where I've gone wrong?

Standard deviation of 19,29,21,22,23

What are the digits that repeat in the smallest sequence of repeating digits in the decimal equivalent of 24/11?

Christine wong has asked dave and mike to her move into a new apartment on sunday morning. she has asked them both, in case one of them does not show up. from past experience, christine knows that there is a 40% chance that dave will not show up and a 30% chance that mik a. what is the probability that both dave and mike will show up? (round your answer to 2 decimal places.) b. what is the probability that at least one of them will show up? c. what is the probability that neither dave nor mike will show up? (round your answer to 2 decimal places.)e will not show up. dave and mike do not know each other and their decisions can be assumed to be independent.