UEC Exam ratio problem

Question

I am going to sit for UEC exam and I am 15 years old and I need helps.

The question is as follow:

If p:q:r=3:5:7 and p+q=56
Find the value of p+q+r

Thank you

What have you tried? What do you know about the relation between $p$ and $q$? — saulspatz, Oct 23 '19 at 15:25
This seems fairly straightforward with a cursory understanding of ratios and it might be helpful to better articulate where you are stuck. Not trying to patronize, but if you don't understand ratios it might be helpful to be explicit about that. — Kitter Catter, Oct 23 '19 at 15:28

score 0 · Answer 1 · answered Oct 23 '19 at 15:30

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Hint: From our starting equation we get $$p:q=3:5$$ so $$p=\frac{3}{5}q$$ and $$q+\frac{3}{5}q=56$$ Can you finish?

answered Oct 23 '19 at 15:30

So $$ \frac{8}{5}q=56$$ then $$q=35$$ From equation we know $$ \frac{q}{r}= \frac{5}{7}$$ then get $$r=49$$ At the end $$p+q+r=56+49=105$$ Is it do like that? – Steve Tan Oct 26 '19 at 12:32
Yes, this is the right result – Dr. Sonnhard Graubner Oct 26 '19 at 12:37
Thanks a lot XD – Steve Tan Oct 27 '19 at 07:29

score 0 · Accepted Answer · answered Oct 23 '19 at 15:33

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Using ratios, $\frac{3q}{5}=p$ so replace $p$ by its expression in terms of $q$:

$\frac{3q}{5}+q=56$ which gives $q=35$ and so $p=21$ and using the ratios given, $r=49$.

So $p+q+r=21+35+49=105$

answered Oct 23 '19 at 15:33

Sina Babaei Zadeh

2 Answers2