Question

two petri dishes were on the desktop in dr. mcfarlans lab. dish a had cells with a radius of 4.8×10⁻¹⁵ cm. dish b had cells that had a radius of 4.7×10⁻¹³ cm. what is the sum of the radii of the two types of cells, using scientific notation?

a. 474.8×10⁻¹⁵ cm

b. 47.48×10⁻¹⁶ cm

c. 4.748×10⁻¹⁷ cm

d. 4.748×10⁻¹³ cm

Explanation:

Step1: Rewrite one number to have the same exponent

Rewrite $4.7\times10^{- 13}$ as $470\times10^{-15}$.

Step2: Add the numbers with the same exponent

$(4.8\times10^{-15})+(470\times10^{-15})=(4.8 + 470)\times10^{-15}=474.8\times10^{-15}$.

Step3: Convert to proper scientific - notation

$474.8\times10^{-15}=4.748\times10^{-13}$ (move the decimal point two places to the left and increase the exponent by 2).

Answer:

D. $4.748\times 10^{-13}$ cm