50,000 contestants participate in an on-line game. The game randomly eliminates 20% of the contestants each day. Determine the n
1 answer:
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Answer:
is the sum of positive integers between
(inclusive) and
(inclusive) that are not multiples of
and not multiples
.
Step-by-step explanation:
For an arithmetic series with:
as the first term,
as the last term, and
as the common difference,
there would be terms, where as the sum would be
.
Positive integers between (inclusive) and
(inclusive) include:
.
The common difference of this arithmetic series is . There would be
terms. The sum of these integers would thus be:
.
Similarly, positive integers between (inclusive) and
(inclusive) that are multiples of
include:
.
The common difference of this arithmetic series is . There would be
terms. The sum of these integers would thus be:
Positive integers between (inclusive) and
(inclusive) that are multiples of
include:
.
The common difference of this arithmetic series is . There would be
terms. The sum of these integers would thus be:
Positive integers between (inclusive) and
(inclusive) that are multiples of
(integers that are both multiples of
and multiples of
) include:
.
The common difference of this arithmetic series is . There would be
terms. The sum of these integers would thus be:
.
The requested sum will be equal to:
- the sum of all integers from
to
,
- minus the sum of all integer multiples of
between
and
, and the sum integer multiples of
between
- plus the sum of all integer multiples of
between
That is:
.