Helen says the sum of two prime numbers is always even. patty disagrees who is correct? Explain your answer
2 answers:
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r=4
V = 268.083
A. We are going to form 7 digit numbers from the set {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
where the first digit cannot be 0 or 1.
so we have 8 choices for the 1. digit, and 10 choices for all the other 6 digits.
this means there are
possible numbers.
b.
consider the numbers which start with 911. There are
such numbers, since for the 4th, 5th, 6th and 7th digits we have 10 choices.
then we remove this number, from the one we found in a:
There are in total
numbers which don't start with 911.
Answer:
a.
b.7,990,000
where the first digit cannot be 0 or 1.
so we have 8 choices for the 1. digit, and 10 choices for all the other 6 digits.
this means there are
b.
consider the numbers which start with 911. There are
then we remove this number, from the one we found in a:
There are in total
Answer:
a.
b.7,990,000
Answer:
Step-by-step explanation:
refers to the permutations of 5 items taken 3 at a time. To evaluate this, we use factorials as follows;
The factorial of an integer n is evaluated as;
Using this concept, the above expression can now be simplified as follows;
Therefore, the permutations of 5 items taken 3 at a time is 60.
The next expression, refers to the combinations of 6 items taken 4 at a time. The simplification utilizes similar concepts of permutations since we shall be involving factorials;
Therefore, the combinations of 6 items taken 4 at a time is 15.
The final step is to evaluate the product;