John, Jack, Jim, and Joe all decided to take up horseback riding. Jim went twice as many times as Jack, and John went four more times than Joe but three less times than Jim. Joe went 15 times altogether. How many times did Jack go?

11 times

Step-by-step explanation:

Given

Required

Find

Substitute in

Substitute in

Collect like terms

Substitute in

Divide both sides by 2

Mean (average) can be found by adding up all the numbers and then dividing that by how many numbers there are.
(5+10+12+4+6+11+13+5) / 8 = 66/8 = 8.25 <==

the mode (the number used most often) = 5just so u know, there doesn't have to be a mode, and sometimes there is more then 1 mode. But for this one, the mode is 5. <==

median (the middle number)...for this, u put the numbers in order...
4,5,5,(6,10),11,12,13
now start moving from both ends going inward until u find the middle number...keep in mind, when u have an odd number of numbers, u will have 1 middle numberbut when there is an even number of numbers, like in this case, u will have 2 middle numbers...so u take ur 2 middle numbers, add them, then divide by 2 to get ur median.
median = (6 + 10) / 2 = 16/2 = 8 <==