<p>At a fixed temperature,the volume of a sample of gas varies
as the pressure of the gas. If the pressure of a sample of gas at a fixed
temperature is increased by 50 %,by what percent is the volume decreased?</p>
<p>1)25%
2)100/3%
3)50%
4)75%
5)100%</p>
<p>In the first problem I tried to solve it by just substituting values.</p>
<p>V = k/P;</p>
<p>100 = 1000/10;</p>
<p>200/3 = 2/3 which is approx 66 %.</p>
<p>If the variable a varies directly as b and inversely as c,and if a = 10x + 5
when c = 2 and b = 10,then what is the value of a when b = 4 and c = 2x + 1?</p>
<p>I believe the first problem should say varies INVERSLY. In this case, VP=k for some constant k. Since the nature of the problem indicates that k doesn’t matter, let k=100. Now, if P=10, then V=10. Now increase P 50% to P=15. Then V~6.67. </p>
<p>It’s not hard to see that this is a 33.3% decrease, but if you don’t just use the percent change formula:</p>
<p>% change = (change/original)*100 ~ (10-6.67)/10 * 100 ~ 33.3%, choice (2).</p>
<p>For the second problem,</p>
<p>a=kb/c. </p>
<p>10x+5 = k(10)/2 = 5k. So k = 2x + 1.</p>
<p>a = (2x + 1)4/(2x + 1) = 4.</p>
<p>Thanks alot DrSteve.</p>