it is 20 the answer isnt included.
(1/15) / (1/3) = 1/x
cross multiply
1/15x = 1/3
x = 1/3 * 15
x = 15/3
x = 5 hrs
The proportion pop/total = 5/7 is presumed to hold for the next 500 songs.
pop/500 = 5/7
pop = 500*5/7 ≈ 357
357 of the next 500 songs downloaded are expected to be pop songs.
This is an arithmetic sequence with first term (a) = 11, number of terms (n) = 57, sum of nth term (Sn) = 19,779.
Let the amount of money she saved more each month be d, then
Sn = n/2(2a + (n - 1)d)
19,779 = 57/2(2(11) + (57 - 1)d)
19,779 = 28.5(22 + 56d)
19,779 = 627 + 1,596d
19,779 - 627 = 1,596d
d = 19,152/1,596 = 12
Therefore, she saved $12.00 more each month.
