arc QS in degrees is 2 x angle QRS
so angle substended at the centre of the circle by QS is 60 degrees
now,
theta/360 x 2pi x r
theta is 60 degrees
radius of the circle is 5 (from the center of P)
so,
60/360 x 2(3.14) x 5
60/360 x 6.28 x 5
= 0.1666 x 31.4
= 5.23124
QS = 5 degrees to the nearest tenth