Question

The width of a red blood cell is approximately 8 micrometers, which is 8 x 10-6 meter. Give your answers to the questions below in scientific notation. Be sure to answer both A and B, and explain your answer to B.
A. What would be the width of 7.2 x 105 red blood cells in meters?


B. If a grain of salt is .5mm wide, how many red blood cells could fit across one grain of salt? Explain your answer. (Hint: 1mm = 1 X 10-3 m.)

Answer 1

Answer:

A. 756

B. 69.44 or 62.5

Step-by-step explanation:

To get the answer for B you first convert 0.5mm to micrometers.

0.5 millimeters = 500 micrometers

Now, we divide 500 by 8

500 ÷ 8 = 62.5

To get the exact result, we divide 500 by 7.2

500 ÷ 7.2 = 69.44

Answer 2

Answer:

A)  $5.76\text{ meters}$

B)  62

Step-by-step explanation:

The width of a red blood cell is approximately 8 micrometers $=8\times 10^{-6}$ meters

Part A)

Width of 1 red blood cell $=8\times 10^{-6}$ meters

width of $7.2\times 10^5$ red blood cells $=7.2\times 10^5\times 8\times 10^{-6}$ meters

                                                                $=7.2\times 8\times 10^5\times 10^{-6}$

                                                                $=57.6\times 10^{-1}$

Now change into scientific notation. So, decimal should be between 1 to 10

Decimal move 1 digit right to left

                                                                $=5.76\times 10^1\times 10^{-1}$

                                                                $=5.76\text{ meters}$

Hence, the width of red blood cells is $5.76\text{ meters}$

Part B)

If a grain of salt is 0.5 mm wide.

First convert mm to m. ( 1 mm = 1 × 10⁻³ m)

Therefore, 0.5 mm = 5 × 10⁻⁴ m

$\text{Number of red blood cells fit}=\dfrac{\text{Size of grain}}{\text{Size of a red blood cell}}$

Size of a grain = 5 × 10⁻⁴ m

Size of a blood cell = 8 × 10⁻⁶ m

$\text{Number of red blood cells fit}=\dfrac{5\times 10^{-4}}{8\times 10^{-6}}$

$\text{Number of red blood cells fit}=62.5$

Hence, 62 number of red blood cells fit in a grain of salt.