<u><em>Answer:</em></u>
The sample has 4200 × 10³ cells red blood cells
<u><em>Explanation:</em></u>
Assume that the number of white blood cells in an average person is w
<u>We are given that:</u>
Number of red blood cells is 6 × 10² times as many as white blood cells
<u>This means that, in average person:</u>
Number of red blood cells = 6 × 10² × number of white blood cells
Number of red blood cells = 6 × 10² × w ................>
<u>We are given that:</u>
A sample of blood has 7 × 10³ white blood cells
To know the number of red blood cells in the sample, we will simply substitute with w = 7 × 10³ in equation I
<u>This is done as follows:</u>
Number of red blood cells = 6 × 10² × w
Number of red blood cells = 6 × 10² × 7 × 10³
Number of red blood cells = 4200 × 10³ cells
Hope this helps :)