In scientific notation, what is the sum of 2.3 times 10^{-3} and 5.4 times 10^{-4}? a. 2.84 times 10^{-3}b. 5.63 times 10^{-3}c. 7.7 times 10^{-7}d. 12.42 times 10^{-12}

2.3 x 10⁻³
5.4 x 10⁻⁴

It is better to add this using standard form because these two have different decimal places.

2.3 x 10⁻³   ⇒  0.00230
5.4 x 10⁻⁴   ⇒  0.00054
                          0.00284

0.00284 in scientific notation is 2.84 x 10⁻³