Posted by Julia Ten on Thursday, July 23, 2009 at 7:40pm.
the average of 20 numbers in a list is 32. when a number is added to the list, the average becomes 34. What number was added to the list?
so i started like this...
x/20= 32
my answer is 640. is this correct?

math  Reiny, Thursday, July 23, 2009 at 8:03pm
no
think backwards, and how "average" is obtained
the average of 20 numbers was 32, so the total of all the numbers must have been 20x32 or 640.
For 21 numbers the average was now 34, so the total must have been 21x34 or 714
so 714640 or 74 must have been the number added
Answer This Question
Related Questions
 math  the mean of a list of seven numbers is 45. if i add two numbers to this ...
 Statistics  A list of numbers has an average of 48 and an SD of 12. The list is...
 Math  In the list of numbers 1,2,3,4,5,6,7,8,9, how many of the numbers in the ...
 Computing: Simple Python  Hi this is the code I'm working on, but every time I ...
 maths  In a list of numbers that starts with the number 13, every number is 4 ...
 math  the difference between two numbers is 5 the average of the number is 11 ...
 5th grade math  A list of numbers represents the following pattern: For each ...
 math  the average of 2 number is 9. list all possible of numbers that will work
 Keyboarding and word processing  If you're compling a list of sources you used ...
 math  Does anyone know how to explain mean, median, mode and range mean?? mean...
More Related Questions