Mean and SD in R -

maybe easy question. data.frame:

> read.table("text.txt")    v1       v2 1  26    22516 2  28    17129 3  30    38470 4  32    12920 5  34    30835 6  36    36244 7  38    24482 8  40    67482 9  42    23121 10 44    51643 11 46    61064 12 48    37678 13 50    98817 14 52    31741 15 54    74672 16 56    85648 17 58    53813 18 60   135534 19 62    46621 20 64    89266 21 66    99818 22 68    60071 23 70   168558 24 72    67059 25 74   194730 26 76   278473 27 78   217860 

it means have 22516 sequences length 26, 17129 sequences length 28, etc. know sequence length mean , standard deviation. know how it, know creating list full of 26 repeated 22516 times , on... , compute mean , sd. however, thing there easier method. idea?

thanks.

for mean: (v1 %*% v2)/sum(v2)

for sd: sqrt(((v1-(v1 %*% v2)/sum(v2))**2 %*% v2)/sum(v2))