A linear series with "i" terms can be summed by finding the average of the first and last terms, then multiplying by the amount of terms.This sequence can be written as follows:
ai= 11 + 1(i-1)
= 11 + i - 1
= 10 + i
11 is the first term, 1 is the difference between terms which gets multiplied by (i-1)
So the fourth term a4= 10 + 4 = 14
Sum total = i * (a1+ ai)/2 (no. of terms * average of first and last term)
= 10 * (11 + 20)/2
= 10 * (31/2)
= 155
12.
the answer is 12.
23
12
The sum of 3/4 and 1/6 is 11/12
11 and 1
11 and 12.
66.
The factors are 1 & 11 !
-11 and -1
It is: 11/12 times 24 = 22
This is easier to solve by looking at the reverse problem, what is the probability of the sum being 11 or more. Out of the 6*6 = 36 outcomes, three (5,6), (6,5) and (6,6) satisfy this event. So the probability of getting a sum of 11 or more is 3/36. So the probability of less than 11 is 1-Pr(>=11) = 1 - 3/36 = 33/36 = 11/12 or 0.91667