Question

The speed of light is about 1.86×10^5 miles per second. The star Sirius is about 5.062×10^13 miles from Earth. About how many seconds does it take light to travel from Sirius to Earth? Write your answer in scientific notation, rounded to the nearest hundredth.

Answer 1

Answer:

2.72 × 10^8 seconds

Step-by-step explanation:

1. Organize the given information to help you create the equation:

- Light travels 1.86 × 10^5 miles per 1 second

- Light travels 5.062 × 10^13 miles per n seconds

- Need to solve for n

2. Set up the equation (Make sure that both numerators and both denominators match units, so the seconds are either both on top or both on bottom, NOT switched):

$\frac{1.86 * 10^5}{1}$ = $\frac{5.062 * 10^1^3}{n}$

3. Cross multiply (Multiply the first fraction's numerator by the second's denominator, and vice versa. It doesn't matter what number is on which side of the = sign)

n × (1.86 × 10^5) = 5.062 × 10^13

4. Solve for n by isolating the variable and dividing.

$\frac{n (1.86 * 10^5)}{1.86 * 10^5}$ = $\frac{5.062 * 10^1^3}{1.86 * 10^5}$

n = $\frac{5.062 * 10^1^3}{1.86 * 10^5}$

n = 2.72 × 10^8 (Make sure to include the unit, seconds)