3,072
3,468
4,242
4,486
7 Answers

♥♦♣♠
first term, a = 3
difference = 9 – 3 = 6
……………..= 15 – 9 = 6
n = 34
S_n = ( n / 2 ) [ 2a + ( n – 1 ) d ]
S_34 = ( 34 / 2 ) [ 2 ( 3 ) + ( 34 – 1 ) ( 6 ) ]
………= 17 [ 6 + ( 33 ) ( 6 ) ]
………= 17 ( 6 + 198 )
………= 17 ( 204 )
………= 3,468
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3, 9, 15, 21, . . . .
a = 3, d = 93 = 6, n = 34
Sn = (34/2)[2*3 + (341)*(6)]
Sn = 17*[6 +198] = 3468 >==============< ANSWER

3+9+15+21+….. 3+(33*6). =n/2*[2a+(n1)d]=34/2*[2*3+33*6]
=17 * [6+198]
=3468
where a=3 first term
d=6 difference between two consequtive terms
n= no of terms

Use Sn formula with n = 34, a = 3 and d = 6. Simple!

It depends what the rest of the terms are. Probably it averages out to 40 or 50, so I would say the answer is 45 or 45 and a half.

3468
Source(s): Used Excel 
3,103