Measurement, STD2 M1 2009 HSC 25b

The mass of a sample of microbes is 50 mg. There are approximately `2.5 × 10^6` microbes in the sample.

In scientific notation, what is the approximate mass in grams of one microbe? (2 marks)

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`2 xx 10^-8\ text(grams)`

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♦♦♦ Mean mark 20%.
IMPORTANT: Can you solve: 8 apples weigh 1kg, what does 1 apple weigh? This is exactly the same concept.

`text(We need to convert 50 mg into grams)`
`50\ text(mg) = 50/1000 = 0.05\ text(g) = 5 xx 10^-2\ text(grams)`

`:.\ text(Mass of 1 microbe)`	`= text(mass of sample)/text(# microbes)`
	`= (5 xx 10^-2)/(2.5 xx 10^6)`
	`= 2 xx 10^-8\ text(grams)`