I think it helps if you write in all the chords.
In the first example, I think the chord should be a II, but I can't say why.
So I think the chord sequence in the first two bars should be I, IV, II, V
Your answer says I, IV, IV, V, which seems acceptable to me, but not as interesting.
In the second example (Baa Baa Black Sheep), the harmony should settle down in bar 4 ("wool"), rather than hang unresolved. So a "I" chord is more appropriate than a V.
Your version would be I, I, IV, V : IV, I, V, I
I think the "correct" version is I, I, IV, I : IV, I, V, I
Edit: first chord in second half of Black Sheep is a IV, not a V