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March 6, 2015

March 6, 2015

Posted by **Jasmine** on Thursday, April 3, 2014 at 7:45am.

(a) Make a table of values of the function for changes in t of 4, starting from t = 0.

(b) Explain why the formula is given by e = f(t) = 100(0.2)t/4.

(c) By a process of guessing, checking and fixing (no logarithms yet!) estimate the time taken for the efficiency to reach 50%. Choose a reasonable level of accuracy.

(d) Show that the halving time is in fact constant by showing that no matter what time we consider, say t = a, if you then add the time found in the previous part, the efficiency is halved.

(e) Use the halving time to make a sketch of the function over an 8 year period.

- Maths please someone help me out!!! -
**Steve**, Thursday, April 3, 2014 at 10:53am.2^(t/4) multiplies by 0.2 every time t increases by 4. That's how the efficiency is described in words.

so, get out your calculator (online or physical) and evaluate some values for t. As a sanity check, 50% is a little more than twice as much as 20%, so expect t to be somewhere around half of the 4-year cycle.

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