If Mr. Bisby wants to know the average of the grades on a test, what measure of central tendency would he be looking at? (Spelling counts so make sure to spell it correctly)

50-60=10

step-by-step explanation:

a is 8.b is 10.c is 10.5. d is -.5

step-by-step explanation:

just minus the smallest number from the biggest.

60: 45 =12: 9 =4: 3 so the answer is 4: 3

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.