# Which of the following is the sum of all the multiples of 3 from 15 to 48?

2
by Babyloves11

2016-02-22T18:57:42+08:00
The sum of all multiples of 3 from 15 to 48 is 378.
• Brainly User
2016-02-23T02:09:15+08:00
Arithmetic sequence:  15,...48

Where:
a₁ = 15
= 48
d (common difference = 3
n = ?

Find n:

= a₁ + (n-1) (d)

48 = 15 + (n- 1) (3)

48 = 15 + 3n - 3

48 = 3n + 12

3n = 48 - 12

3n/3 = 36/3

n = 12  The are 12 terms or multiples of 3 from 15 to 48.

Solve for the sum of the sequence (arithmetic series):

()

S₁₂ = 12/2 (15 + 48)

S₁₂ = 6 (63)

S₁₂ = 378

ANSWER:  The sum of multiples of 3 from 15 to 48 is 378.