Four types of batteries ((1) alkaline, no-name brand; (2) alkaline, name brand;

Question

Four types of batteries ((1) alkaline, no-name brand; (2) alkaline, name brand; (3) heavy-duty, no-name brand; (4) heavy-duty, name brand) were each tested to exhaustion in a circuit where the battery powered both a light-bulb and an electric clock in parallel. The clock was 'zeroed' initially and the elapsed time on it when it stopped was taken as a measurement of battery life. The experiment was replicated four times and all 16 observations made in random order over a two-week period. Answer the following questions, with due regard for the assumptions behind the analysis, using the data from the above experiment. (a) What type of non-rechargeable flashlight battery is most economical?

Explanation / Answer

(a)

Mean lifetime for type 1: (602+529+534+585)/4 = 562.5

Price = 0.985$

Price per minute = 0.985/562.5 = 0.00175 $/min

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Mean lifetime for type 2: (863+743+773+840)/4 = 804.75

Price = 0.935$

Price per minute = 0.935/804.75 = 0.001161 $/min

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Mean lifetime for type 3: (232+255+200+215)/4 = 225.5

Price = 0.520$

Price per minute = 0.520/225.5 = 0.00230 $/min

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Mean lifetime for type 4: (235+282+238+228)/4 = 245.75

Price = 0.495$

Price per minute = 0.495/245.75 = 0.00201 $/min

Comparing the average price per minute, we see that type 2 has the lowest value and is thus most economical of all.

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