# Problem of the Day: 2/2/13

The 21st term in an arithmetic sequence is 47. What is the sum of the 12th and 30th terms in the sequence?

Solution to yesterday’s problem:

In order for Amelia to have a 90 average in math, the sum of all her test scores divided by 6 should be at least 90. The total of her scores so far is 85 + 95 + 93 + 88 + 97 = 458, and her last test is unknown so we’ll call it x. An equation for this situation would be

$\frac{458+x}{6}=90$

Solving this equation:

$458+x=540$

$x=82$

So Amelia must make at least an 82 on her last test to keep an A in math.