Answer:it sent 6945 during the 30 day marketing campaign
Step-by-step explanation:
Their goal is to increase the number of emails sent per day by 15 each day. The rate at which they increased the number of mails sent is in arithmetic progression.
The formula for determining sum of n terms of an arithmetic sequence is expressed as
Sn = n/2[2a + (n - 1)d]
Where
a represents the first term of the sequence.
n represents the number of terms.
d = represents the common difference.
From the information given
a = 14
d = 15
n = 30
We want to find the sum of 30 terms, S30. It becomes
S30 = 30/2[2 × 14 + (30 - 1)15]
S30 = 15[28 + 435]
S30 = 6945