3.58 6.82 8.36 11.30 14.50 18.20 90 2.58 4.72 5.78 7.89 10.83 16.92 100 2.58 4.72 5.78 7.89 10.83 16.92 150 2.58 4.72 5.78 7.89 10.83 16.92 165 2.58 4.72 5.78 7.89 10.83 16.92 200 2.58 4.72 5.78 7.89 10.83 16.92 250 2.58 4.72 5.78 7.89 10.83 16.92 300 2.58 4.72 5.78 7.89 10.83 16.92 350 2.58 4.72 5.94 6.95 9.24 14.91 400 2.57 4.37 4.91 6.17 8.33 13.21 450 2.50 3.97 4.44 5.56 7.45 11.81 500 2.40 3.65 4.07 5.06 6.74 10.65 700 2.06 2.82 3.10 3.75 4.88 7.51       Exhibit 9.10 shows the average life for the six PAC bonds and the support bond in Deal 5 at various prepayment speeds. From a PAC bond in Deal 4 with an average life of 7.26, we have created six PAC bonds with an average life as short as 2.58 years (P-A) and as long as 16.92 years (P-F) if prepayments stay within 90 PSA and 300 PSA. As expected, the average lives are stable if the prepayment speed is between 90 PSA and 300 PSA. Notice that even outside this range the average life is stable for several of the shorter PAC bonds. For example, PAC P-A is stable even if prepayment speeds are as high as 400 PSA. For the PAC P-B, the average life does not vary when prepayments are between 90 PSA and 350 PSA. Why is it that the shorter the PAC, the more protection it has against faster prepayments? To understand why this is so, remember that there are $156.2 mil- lion in support bonds that are protecting the $85 million of PAC P-A. Thus, even if prepayments are faster than the initial upper collar, there may be sufficient support bonds to assure the satisfaction of the sched- ule. In fact, as can been from Exhibit 9.10, even if prepayments are 400 PSA over the life of the collateral, the average life is unchanged. Now consider PAC P-B. The support bonds are providing protection for both the $85 million of PAC P-A and $93 million of PAC P-B. As     can be seen from Exhibit 9.10, prepayments could be 350 PSA and the average life is still unchanged. From Exhibit 9.10 it can be seen that the degree of protection against extension risk increases the shorter the