Stuart put $99 into a CD that pays 2.6% interest, compounded monthly. According to the Rule of 72, approximately how long will i
2 answers:
Answer: 27 years (approx)
Step-by-step explanation:
According to the Rule of 72,
If the product of interest rate and time is equal to 72, the amount will be doubled.
According to the question,
The annual rate = 2.6%
Let after t years the amount will be doubled.
Thus, 2.6 × t = 72
Since, the actual time will always less than the time gets by the 72 rule.
Thus, Approx 27 year after the amount will be doubled.
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9514 1404 393
Answer:
m^2 = 35/9
Step-by-step explanation:
The line will be tangent to the ellipse where there is one point of intersection between the line and the ellipse. We can find that case by looking at the discriminant of the quadratic.
x^2 +9(mx +2)^2 = 1
x^2 +9(m^2x^2 +4mx +4) = 1
(9m^2 +1)x^2+36mx +35 = 0 . . . . subtract 1, collect terms
__
Then the discriminant is ...
(36m)^2 -4(9m^2 +1)(35)
We want it to be zero, so we have ...
1296m^2 -1260m^2 -140 = 0 . . . . eliminate parentheses
36m^2 = 140 . . . . . . . . . . . . . . . add 140
m^2 = 140/36 . . . . . . . . . . . . divide by 36
m^2 = 35/9
