21.
A triple riveted butt joint with double straps of unequal width is to be designed for a boiler shell. The pitch of the rivets in the outer row is double the pitch in the inner row and zigzag riveting is proposed. Which of the following statement is correct?

22.
Which of the following statement is correct?

23.
Which of the following statement is correct?

24.
Which of the following statement is correct?

25.
Which of the following statement is correct?