A deck of cards contains red cards numbered
1
,
2
,
3
,
4
, blue cards numbered
1
,
2
,
3
,
4
,
5
,
6
and green cards numbered
1
,
2
,
3
,
4
,
5
,
6
,
7
,
8
,
9
,
10
,
11
,
12
,
13
. If a single card is picked at random, what is the probability that the card is red?

Give your answer as a fraction.