Practice: Activating Prior Knowledge

Mathematics

1 answer:

Elena-2011 [213]3 years ago

4 0

Scientific notation is used to write really large numbers, or really small numbers using less digits. For example:

1. Earth's distance from the sun 150,000,000 kilometers. We can rewrite this in scientific notation as 1.5 x $10^{8}$

2. The length of a skin cell is 0.00003 meters. We can rewrite this in scientific notation as 3.0 x $10^{-5}$

3. The world population is about 7,000,000,000. We can rewrite this in scientific notation as 7 x $10^{9}$

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Rufus appears before Bill and Ted and offers them a bogus proposition: they must paint a house together with their magical guita

jolli1 [7]

Answer:

6.79

Step-by-step explanation:

-Let X denote the total amount of the job.

-The job has to be done in 5 hrs, therefore the portion done every hour is:

$Rate=\frac{Total}{Time}\\\\=\frac{X}{5}\\\\=\frac{1}{5}X=0.2X$

Therefore, the rate of Bill and Ted working jointly must equal the rate calculated above:

$R_{Bill}=\frac{X}{19}\\\\=\frac{1}{19}X\\\\R_{Bill}+R_{Ted}=R_{required}\\\\\frac{1}{19}X+R_{Ted}=\frac{1}{5}X\\\\R_{Ted}=\frac{1}{5}X-\frac{1}{19}X\\\\=\frac{14}{95}X\\\\\therefore \frac{14}{95}X=1\ hr\\\\X=1\div \frac{14}{95}\\\\=6.7857\approx 6.79$ $hrs$