Shear Stress in Circular Section

Q. What is the ratio of maximum shear stress to average shear stress for a circular section?

1. 2
2. 2/3
3. 4/3
4. 3/4

Q. Consider the following statements :
1. In a beam, the maximum shear stress occurs at the neutral axis of the beam cross-section.
2. The maximum shear stress in a beam of circular cross-section is 50% more than the average shear stress.
3. The maximum shear stress in a beam of triangular cross-section, with its vertex upwards occurs at b/6 above the neutral axis.

Which of these statements are correct?

1. 1, 2 and 3
2. 2 and 3 only
3. 1 and 2 only
4. 1 and 3 only