桃子

Your graphs are clearly wrong.

y=tan x passes through (45 deg, 1).
y=2 tan x passes through (45 deg, 2).

y=tan x has a period of 180 deg.
y=tan (x/4) has a period of 45 deg.

桃子

Draw the line y=1 and count the number of intersection.

桃子

It looks right.

For part (c), just read the intersection from the graph.

桃子

In any graphical question, small errors will be allowed.

桃子

As a note, this question may also be solved exactly.

3 sin 2x = 1
sin 2x = 1/3
.....

Even in graphical question, you may solve algebraically as a check.