Let r = number of reinforced panels, so standard panels = 10 - r, where r can be 1 through 9.
Total clips = 16r + 11(10 - r) = 16r + 110 - 11r = 5r + 110.——— is r > 4?
Statement (1): Total clips is a multiple of 9
5r + 110 must be divisible by 9.
110 = 12 × 9 + 2, so 110 leaves remainder 2 when divided by 9.
So 5r must leave remainder 7 when divided by 9 (since 2 + 7 = 9).
Testing r = 1 to 9:
5(1)=5, 5(2)=10, 5(3)=15, 5(4)=20, 5(5)=25, 5(6)=30, 5(7)=35, 5(8)=40, 5(9)=45
Remainders when divided by 9: 5, 1, 6, 2, 7, 3, 8, 4, 0
Only r = 5 gives remainder 7.
So r = 5, which means exactly 5 reinforced panels, and 5 > 4.
Statement (1) alone is
SUFFICIENT.
Statement (2): Switching to 3 reinforced and 7 standard would use at least 10 fewer clips
Clips under new arrangement = 5(3) + 110 = 125.
Current clips = 5r + 110.
Condition: (5r + 110) - 125 ≥ 10, so 5r - 15 ≥ 10, giving 5r ≥ 25, meaning r ≥ 5.
Since r can be 5, 6, 7, 8, or 9, So r ≥ 5, which does confirm r > 4 in all valid cases.
Statement (2) alone is
SUFFICIENT. ——— D