Answer:
Sister is correct.
Explanation:
Given:
Starting distance a = 500 m
Extend ever day d = 250 m
Final distance = 5 km = 5,000 m
Find:
Number of days n
Computation:
An = a + (n-1)d
5,000 = 500 + (n-1)250
n = 19 days
Number of days n = 19 days
Sister is correct.