At what time, between 3 o’clock and 4 o’clock, both the hour hand and minute hand coincide each other ?

Coincide means 00  angle.

This can be calculated using the formulafor time A to B means  [11m/2 - 30 (A)]

Here m gives minutes after A the both hands coincides.

Here A = 3, B = 4

0 =11m/2 –30 × 3
11m = 90 × 2 = 180
m= 180/11 = 16 ⁴/₁₁

So time = 3 : 16 ⁴/₁₁