There may be a small loss of resolution in images if you try to resize them within Word. You should create and edit your images outside Word and import them 'as-is'. Then the conversion process will keep them the same size.
Separately, I recommend that you don't use images to represent tables containing text - use a table instead! This is essential for people with vision impairments who use screenreaders, and it is also much better for people reading your material on a small form-factor device like a mobile phone.
Separately, I recommend that you don't use images to represent tables containing text - use a table instead! This is essential for people with vision impairments who use screenreaders, and it is also much better for people reading your material on a small form-factor device like a mobile phone.