According to the duration, the change is 2%*10.34=20.68% and then corrected according to the convexity. It must be less than 20.68%, so choose 17.65%. The specific change =-2%*10.34+(1/2)*151.60*2%*2%=

-17.648% As for the question that bothers you about why you need to divide by 2 when calculating convexity, because duration is the first derivative of the change in interest rates, and convexity is the second derivative of the change in interest rates. The second term of the expansion of the Taylor series is to be multiplied by

One-half, if there is a third derivative, more precisely, the coefficient of the third derivative is one-sixth.

This is a purely mathematical question.

You need to remember this formula when you take the exam.