Question 1137495
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<pre>
From the condition, you have this general formula

    V = {{{k*(T/P)}}},

where " k " is  a constant value.
    


From the condition, you also have these two expressions for two states of the gas:

    120 = {{{k*(310/18)}}}    (1)

and

    100 = {{{k*(320/P)}}},    (2)

where P is the unknown pressure under the question.



Divide expression (1) by expression (2) (both sides).  You will get


    {{{120/100}}} = {{{((310/18))/((320/P))}}},   or

     1.2 = {{{(310*P)/(18*320)}}}.

which implies

     P = {{{(1.2*18*320)/310}}} = 22.297   atmospheres.    <U>ANSWER</U>
</pre>

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It is the shortest way to solve such problems.


The other approach with calculating the constant value " k " forces you to make unnecessary calculations on the way to the answer.