Question

Find the sum of the odd integers between 24 and 50

Answer 1

Answer:

  481

Step-by-step explanation:

There are several ways you can get there.

1. There are only 13 numbers, so you can write them down and add them up.

  25 + 27 + 29 + ... + 47 + 49 = 481

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2. You can use the formula for the sum of an arithmetic sequence. This one has a starting value of 25, an ending value of 49, and 13 terms.

  Sum = ((start) + (end))/2 × (number of terms) = (25 +49)/2×13 = 481

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3. You can use a formula for the terms of the series and evaluate the sum.

  an = 25 +2(n -1) = 2n +23

$\sum\limits_{n=1}^{13}{(2n+23)}=2\sum\limits_{n=1}^{13}(n)+\sum\limits_{n=1}^{13}{(23)}=2\dfrac{13\cdot 14}{2}+13\cdot 23=481$