Askier has decided that on each trip down a slope, she will do 3 more jumps than before. on her first trip she did 5 jumps. derive the sigma notation that shows how many total jumps she attempts from her third trip down the hill through her tenth trip. then solve for the number of total jumps from her third to tenth trips.

172

Explanation:

The no of jumps makes an A.P series whose first term a is 11 and commom difference d is 3.

Any n the term = a + ( n-1 ) d

first term = a

second term a + d

third term a + 2d

n-1 the term = a + (n-2)d

n th term = a + (n-1) d

∑ ( sum of n ) = a + (a +d ) + ( a + 2d ) + [a +(n-2)d ]+[a+(n-1)d]

∑ =                   =[a+(n-1)d] +[a +(n-2)d ]+ (a + d) + a

the second series have been written by reversing the term of series

Adding the two series , we get

2∑ = [2a+(n-1)d] +[2a+(n-1)d] +          [2a+(n-1)d] + [2a+(n-1)d]

∑ =  1/2x n[2a+(n-1)d]

Here n = 8 , a = 11 , d = 3

∑ = 1/2 x 8 x ( 22 + 21)

= .5 x 8 x 43 = 172

the answer is kevlar