Answer:
21. y = 75000·0.935^t
22. after 74.6 days
23. y = 27.8112·1.18832^t
24. 18.8% per month
25. 1748
Step-by-step explanation:
22. It is convenient to use the graphing calculator to solve this problem. The number of days is where the exponential curve has the value 500. It is about 74.55 days. (see the first attachment)
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23. y = 27.8112·1.18832^t (see the second attachment)
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24. The rate of change is the difference between the base of the exponential and 1, often expressed as a percentage. The time period is the units of t.
(1.18832 -1) × 100% ≈ 18.8% . . . . per month
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25. Evaluating the function for t=24 gives y ≈ 1748.30425259 ≈ 1748.
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<em>Comment on graphing calculator</em>
A graphing calculator can make very short work of problems like these. It is worthwhile to get to know how to use one well.
Two squares root. Because 3 * 3 = 9 and -3 * -3 = 9.
If George's driveway is a rectangle 12.2 m by 3.0 m, its dimensions in cm are
... 1220 cm long × 300 cm wide × 2 cm deep
Thus the volume of gravel required is
... (1220 × 300 × 2) cm³ = 732,000 cm³
George needs about 0.732 bags, so he will probably need to buy 1 bag.
The cordoned are 7.8 and 466.0006