A classroom has 3 rows of desks. There are 5 desks in each row. How many desks are there altogether?
2 answers:
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A proportion looks like this:
It means that the quantity a,b,c and d are in the same proportion: the ratio between a and b is the same ratio between c and d.
They are particularly useful in situation when you have an example given, and you want to extrapolate the relationship for another couple.
For example, you can think of the following problem: "Five apples cost 2 dollars. How much will 8 apples cost?"
You can build the proportion
And then solve it for x:
Answer:
4 + 12 + 36 + ...
Step-by-step explanation:
4, 12, 36, ... is a geometric sequence, it has a common ratio of
When we add the terms of a geometric sequence we get a geometric series.
4+12+36+ ... is a geometric series, it has a common ratio of
4 + 12 + 20 + ... is not a geometric series because it has no common ratio
The second choice is correct