The heights of English men aged 25 to 34 are normally distributed with mean 178 cm and standard deviation 8 cm .
Three English men aged 25 to 34 are chosen at random.
Find the probability that all three men have a height less than 194 cm .
The diagram shows the distribution of heights of Scottish women aged 25 to 34 .
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The distribution is approximately normal. Use the diagram in the Printed Answer Booklet to estimate the standard deviation of these heights, explaining your method.