175 mL at 25% concentration of alcohol contains 0.25 (175 mL) = 43.75 mL of alcohol. If <em>v</em> is the amount of the 70% solution that you use, then that amount contains 0.7<em>v</em> mL of alcohol.
Mixing these two yields a total volume of 175 mL + <em>v</em>, and it contains 43.75 mL + 0.7<em>v</em> alcohol. You want to end up with a concentration of 45%, which means the ratio of the amount of alcohol to the total volume needs to be 0.45:
(43.75 mL + 0.7<em>v</em>) / (175 mL + <em>v</em>) = 0.45
Solve for <em>v</em> :
43.75 mL + 0.7<em>v</em> = 0.45 (175 mL + <em>v</em>)
43.75 mL + 0.7<em>v</em> = 78.75 mL + 0.45<em>v</em>
0.25<em>v</em> = 35 mL
<em>v</em> = 140 mL
Answer:
Step-by-step explanation:
sai đề
Answer:
P = (2, 7)
Step-by-step explanation:
You want to find coordinates of P on segment AB such that P is 3/4 is of the way from A to B.
<h3>Equation for P</h3>
For some fraction q of the distance from A to B, the point P that lies at that fraction of the distance is given by ...
P = A +q(B -A) = (1 -q)A +qB
<h3>Application</h3>
For q = 3/4, the location of P is ...
P = (1 -3/4)A + 3/4B = (A +3B)/4
Using the given point coordinates, we have ...
P = ((-4, -2) +3(4, 10))/4 = (-4 +12, -2 +30)/4 = (8, 28)/4
P = (2, 7)
Answer:
2.30
Step-by-step explanation:
The side of interest is opposite the given angle, and the hypotenuse is given. The sine relation tells you ...
sin(A) = a/c
a = c·sin(A) = 3·sin(50°)
a = BC ≈ 2.2981 ≈ 2.30
