The students of a school decided to beautify the school on Annual Day by fixing colourful flag on the street passage of the school. they have 27 flags to be fixed at intervals of every 2 meter. the flag of stored in the position of the middle most flag. Ruchi was given the responsibility to placing the flag. Ruchi kept her books where the flags were stored. she could carry only one at a time what is the maximum distance she travelled carrying a flag
Answers
answer ;Let A be the middle- most point and 13 flags are fixed at points A1, A2 , A3 ....A13 to the left of A and remaining to the right of A.
Distance travelled for fixing & coming back to A for
(i) first flag = (2+2)m = 4m = a
(ii) second flag = (4+4)m = 8m = a2
(iii) third flag = (6+6)m = 12m = a3
∴ a, a2 , a3 ... from an AP in which a = 4 , a2 = 8 , a3= 12.... n = 13 and common difference, d = 8 - 4 = 4.
Sn = ( n /2) [ 2a = (n -1) d]
∴ S 13 = 13 2 [2 × 4 + (13 - 1)4]
= 13 2 (8+48)
= 13 2 × 56
= 364
∴ Distance travelled to fix 13 flags to the left of A = 364m
Simillarly, distance travelled to fix remaining 13 flags to the right of A = 364m
∴ Total distance travelled = 2 × 364 m
= 728 m
Answer:
728 m is the answer......