Bond J is a $3\%$ coupon bond. Bond K is a $9\%$ coupon bond. Both bonds have $15$ years to maturity, make semiannual payments, and have a YTM of $6\%.$ If interest rates suddenly rise by $2\%,$ what is the percentage price change of these bonds? What if rates suddenly fall by $2\%$ instead?

What does this problem tell you about the interest rate risk of lower coupon bonds?