HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010

(ii) Predict N for t = 15 hours.

In the

PLOT view, press up arrow to move the cursor onto the

curve of best fit. Now press

and enter the value 15. The

cursor will jump to the predicted value for x=15, which is

currently off screen.

Alternatively, change to the

HOME view and use the PREDY

function.

Result: 268 269 colonies.

(iii) Find t so that

N = N

Step 1. Find the values of

and k and store N into memory A

and k into memory K, so that it is un-necessary to re-type them.

See page 135 for instructions on finding the parameters from

the exponential fit curve.

Step 2. Switch to the Solve aplet and enter the equation to be solved.

Changing into the

NUM view, you should find the values of A

and

K already defined, so move the highlight to T and press

Result: Doubling time is 1.0536 hours.

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