Question

A culture of 1.75×1018 bacteria is in petri dish A. A culture of 6.25×1015 bacteria is in petri dish B. How many times greater is the number of bacteria in petri dish A than petri dish B? Enter your answer, in standard notation, in the box.

Answer 1

Dish A has n₁ = 1.75 x 10¹⁸ bacteria.
Dish B has n₂ = 6.25 x 10¹⁵ bacteria.

Calculate n₁/n₂.
$\frac{n_{1}}{n_{2}} = \frac{1.75 \times 10^{18}}{6.25 \times 10^{15}} =0.28 \times 10^{18-15} = 0.28 \times 10^{3} =2.8 \times 10^{2}$

The number of times that the number of bacteria in dish A is greater than the number of bacteria in dish B is 2.8 x 10² in standard notation.

Answer: 2.8 x 10²