Answer:
5 + 2x = 6
2x = 6-5
2x = 1
x = 0.5
n -3n = 14 -4n
-2n = 14-4n (since 4n is negative, change the sign to make it positive and then add 4n to both sides of the equation)
2n = 14
n = 7
7 (5a - 4) - 1 = 14 - 8a
35a - 28 - 1 = 14 -8a
35a -29 = 14 - 8a
43a = 43
a = 1
The normal rule to remember is 68-95-99.7, i.e. plus or minus three sigma corresponds to 99.7% of the probability. That leaves 0.3% in the two tails, or 0.15% in the tail above 3 sigma.
Answer: 0.15%
