15
11
13
11.. 7+4=11 and 15-4=11
The square root of a number between 10 and 11 can be approximated by finding the average of the square roots of 10 and 11. The square root of 10 is approximately 3.1623, and the square root of 11 is approximately 3.3166. Therefore, the square root of a number between 10 and 11 would be approximately 3.23945.
the halfway point is 10.5 or 10 and a half
There is no "the" rational" number since there is an infinity of them. Start with the number halfway between the two: (1/10+1/11)/2 = 21/220. Then try halfway between 1/10 and 21/220, and then halfway between 1/10 and that on. And so on.
15
11
13
It is 13
11.. 7+4=11 and 15-4=11
8
the number between 2 and 20 is 11
The number 8 is halfway between 5 and 11. It is 3 more than 5 and 3 less than 11. To find a halfway point (which is also the average), add the numbers together and divide by 2.
It is (10.7 + 11)/2 = 10.85
It is 47, the number halfway between the two of them.