Say r is rational. Suppose for a second, that s is not. Then, r+s is irrational. But this contradicts the fact that b is rational.
So, if one root is rational, then the other root is also rational
First, convert the 65% to a real mathematical number. For percents, this is always done by dividing the 65% by 100%, or 65% / 100% = 0.650.
Second, find out what 65% of $60 is. This is the amount of the sale discount. This is always found by mulitplying 0.650 by the item's cost $60, like this:
0.650 x $60 = $39.00.
So for this sale, you'll save $39.00 on this item.
This means, the cost of the item to you is
<span>$60 - $39.00 = $21.00.</span>
The value that is 2 standard deviations from the mean is; 130
<h3>What is Empirical Rule?</h3>
For this question, we will use Z-score and as such whether the value is below or above mean (shown by positive or negative sign) and by how much (times the standard deviation).
Thus;
Calculated value = μ + zσ
where;
μ is mean
σ is standard deviation
Hence, the value that would be +2 standard deviations from the mean is;
Calculated value = 100 + 2(15)
Calculated value = 130
Read more about Empirical Rule at; brainly.com/question/10093236
