40% of a number is 68.What is the number?
1 answer:
You might be interested in
<h3>Answer: 6</h3>
===========================================================
Explanation:
Rule: If a set has n elements in it, then it will have 2^n subsets.
For example, there are n = 3 elements in the set {a,b,c}. This means there are 2^n = 2^3 = 8 subsets. The eight subsets are listed below.
- {a,b,c} .... any set is a subset of itself
- {a,b}
- {a,c}
- {b,c}
- {a}
- {b}
- {c}
- { } ..... the empty set
Subsets 2 through 4 are subsets with exactly 2 elements. Subsets 5 through 7 are singletons (aka sets with 1 element). The last subset is the empty set which is a subset of any set. You could use the special symbol to indicate the empty set.
For more information, check out concepts relating to the power set.
-------------------
The problem is asking what value of n will make 2^n = 64 true.
You could guess-and-check your way to see that 2^n = 64 has the solution n = 6.
Another approach is to follow these steps.
Which is fairly trivial.
Or you can use logarithms to solve for the exponent.
Due to rounding error, we don't land exactly on 6 even though we should.