E = 352.50 euro × 1 pound / 1.41 euro = 250.00 pounds
J = 39856 yen × 1 pound / 188 yen = 212.00 pounds
a) Japan is cheaper
b) 250 - 212 = 38 pounds cheaper
I prefer to use compatible numbers because by using this method it is easier to make a sum mentally. This is true because compatible numbers are close in value to the actual numbers. For a better understanding, let's take an example:
Suppose you have two numbers, namely 640 and 40. These two numbers are compatible for division because:
64 ÷ 4 = 16
So, we have used mental arithmetic to solve a more complex problem.
<span>In a normal distribution 68.27% of the values are within one standard deviation from the mean, 95.5% of the values are within two standard deviations from the mean, and 99.7 % of the values are within three standard deviations of the mean
With that you have the answer to the three questions:
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<span>a. significantly high (or at least 2 standard deviations above the mean).
99.5% of the values are within 2 standard deviations from the mean, half of 100% - 95.5% = 4.5% / 2 = 2.25% are above the mean, so the answer is 2.25%
b. significantly low (or at least 2 standard deviations below the mean).
The other half are below 2 standard deviations, so the answer is 2.25%
c. not significant (or less than 2 standard deviations away from the mean).
As said, 95.5% are within the band of two standard deviations from the mean, so the answer is 95.5%.
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