According to the rule of 72, if you deposit $100 in an account that pays 9% compound
interest, how long will it take that initial deposit
to reach $200?

Compound Interest works in a continuous pattern.

The formula is x = 100*(1.09)^y

x = the amount received after interest.

y = the number of years

x = 100*(1.09)^9

x = $217.19

It would take 9 years for the initial deposit to reach $200

a manufacturer of printed circuit boards uses exponential smoothing with trend to forecast monthly demand of its product. at the end of december, the company wishes to forecast sales for january. the estimate of trend through november has been 200 additional boards sold per month. average sales have been around 1000 units per month. the demand for december was 1100 units. the company uses α = 0.20 and β = 0.10. make a forecast including trend for the month of january.

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"we first find value of tax in dollars.

the difference between the two prices   is: 23. 54 - 22 = 1.54

therefore the sales tax in dollars is 1.54

the tax % will be   (amount of tax / original cost price ) × 100

(1.54 / 22) × 100  → (0.07) × 100 =   7

so the tax rate is 7%

we can double check the answer.

7 % of 22   → (7/100) × 22 → 0.07 × 22 = 1.54

22 + 1.54 = 23.54"