Solve the problem 4y+3=19 using mental math
2 answers:
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Using the fundamental counting theorem, we have that:
- 648 different area codes are possible with this rule.
- There are 6,480,000,000 possible 10-digit phone numbers.
- The amount of possible phone numbers is greater than 400,000,000, thus, there are enough possible phone numbers.
The fundamental counting principle states that if there are p ways to do a thing, and q ways to do another thing, and these two things are independent, there are ways to do both things.
For the area code:
- 8 options for the first digit.
- 9 options for the second and third.
Thus:
648 different area codes are possible with this rule.
For the number of 10-digit phone numbers:
- 7 digits, each with 10 options.
- 648 different area codes.
Then
There are 6,480,000,000 possible 10-digit phone numbers.
The amount of possible phone numbers is greater than 400,000,000, thus, there are enough possible phone numbers.
A similar problem is given at brainly.com/question/24067651
The point of intersection is the point where lines intersect.
<em>There will be 595 intersections for 35 lines, where no 3 lines are concurrent.</em>
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Given
<em /><em> --- the number of lines</em>
<em /><em> --- no three lines are concurrent</em>
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When no three line are concurrent, it means that no three lines meet at the same point.
<u>So, the sequence of intersection is:</u>
- <em>0 intersection for 1 line</em>
- <em>1 intersection for 2 lines</em>
- <em>3 intersections for 3 lines</em>
- <em>6 intersections for 4 lines</em>
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Following the above sequence, the number of intersections for n lines is:
In this case,
So, we have:
<em>Hence, there will be 595 intersections for 35 lines, where no 3 lines are concurrent.</em>
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Read more about lines of intersections at: