DNA is approximately 2.5 nmnm in length. If an average man is 5 ft 10 in. in. tall, how many DNA molecules could be stacked to extend from the ground to the top of the head of an average man?

7.112 * 10⁸.

Explanation:

The length of DNA is 2.5 nm = 2.5 * 10⁻⁹m.

The average human length = 5 ft 10 in = 70 inch.

1 inch = 0.0254 m.

70 inch = 70 * 0.0254 = 1.778 m.

Number of DNA molecules = length of man / length of DNA.

Number of DNA molecules = 1.778 m / 2.5 * 10⁻⁹m.

Number of DNA molecules = 7.112 * 10⁸.

Thus, the answer is 7.112 * 10⁸.