63/3= 21
So 21 miles per gallon of gas
To find 7, you multiply it by 7
21*7= 147
147 miles on 7 gallons of gas
#9 You have to make the fraction a decimal, then multiply 11.8 by 6.5. This is because 11.8 is per hour.
#10 here is a hint, one quarter of an hour is 15 minutes. again change the fraction to a decimal
#11 just multiply the 2 numbers
1.4
×2.9
---------
126
+ 280
------------------
3.06
To find the y-intercept, simply set the value of x equal to 0, and solve for y, or f(x).
f(x) = 0^2 - 3(0) - 40
f(x) = -40
<h3>The y-intercept is -40.</h3>
Because this is a 2nd degree polynomial, we cannot find the x-intercepts in one step, and must instead use one of a few different methods.
In this case, we're going to use the quadratic formula:
Plug in the values.
3 +/- √(-3^2 + 160) / 2
3 +/- √169 / 2
3 +/- 13 / 2
(3 + 13) / 2 = 16 / 2 = 8
(3 - 13) = -10 / 2 = -5
<h3>The x intercepts are 8, and -5.</h3>
We need the half-life of C-14 which is 5,730 years.
Now, we will need a half-life equation:
elapsed time = half-life * log (bgng amt / ending amt) / log 2
We'll say beginning amount = 100 and ending amount = 41
elapsed time = 5,730 * log (100/41) / log 2
elapsed time = 5,730 * log (
<span>
<span>
<span>
2.4390243902
</span>
</span>
</span>
) / 0.30102999566
elapsed time = 5,730 * 0.38721614327 / 0.30102999566
elapsed time =
<span>
<span>
</span></span><span><span><span>5,730 * 1.2863041851
</span>
</span>
</span>
<span>elapsed time = 7,370.523 years
Source:
http://www.1728.org/halflife.htm </span>
What are you stuck on ??????
