Question

the mass of a red blood cell is about 2.8×10⁻¹¹ grams. a person has about 2.5×10¹³ red blood cells in their body. what is the total mass of red blood cells in grams? a. 7.0×10² b. 7.0×10²⁴ c. 7.0×10⁻²⁴ d. 7.0×10³

Explanation:

Step1: Recall multiplication rule of scientific - notation

To find the total mass, multiply the mass of one red - blood cell by the number of red - blood cells. If we have two numbers in scientific notation \(a\times10^{m}\) and \(b\times10^{n}\), their product is \((a\times b)\times10^{m + n}\).
The mass of one red - blood cell is \(m = 2.8\times10^{-11}\) grams and the number of red - blood cells is \(N=2.5\times 10^{13}\).

Step2: Perform the multiplication

\[

$$\begin{align*} m_{total}&=(2.8\times10^{-11})\times(2.5\times 10^{13})\\ &=(2.8\times2.5)\times(10^{-11}\times10^{13})\\ &=7.0\times10^{-11 + 13}\\ &=7.0\times10^{2} \end{align*}$$

\]

Answer:

A. \(7.0\times 10^{2}\)