Ratio Boxes

[gallup2010]

Problem 1: Sparrows and crows perched on the wire in the ratio of 5 to 3. If the total number of sparrows and crows on the wire was 72, how many crows? Need help with first one so I can complete the other problems.

 

[Denis]

Hint: 5S:3C, 5S:3C, ..... until total = 72

 

[Loren]

Another hint. For every group of 8, 5 of them are sparrows and 3 of them are crows. How many groups of eight are there in the total number of birds?

 

[gallup2010]

Thank you. There are 27 crows. I think I understand enough to finish the rest of my homework

 

[masters]

The ratio \(\displaystyle \frac{S}{C}=\frac{5}{3}\) says that the ratio of Sparrows (S) to Crows (C) is \(\displaystyle \frac{5}{3}\).

The total number of birds here is 8.

The ratio of Sparrows (S) to the Total (T) would be \(\displaystyle \frac{S}{T}=\frac{5}{8}\), while the ratio of Crows (C) to the Total (T) would be \(\displaystyle \frac{C}{T}=\frac{3}{8}\).

Set up a proportion using the new Total of 72 birds and solve for C:

\(\displaystyle \frac{C}{T}=\frac{3}{8}=\frac{C}{72}\)

 

[Denis]

5:3 = 8
72 / 8 = 9
9 * 3 = 27