The value of  t0.875t0.50 for nth order reaction A→  Productis :

t=1(n−1)k1(a−x)n−1−1an−1⇒t87.5t50=1(n−1)K1(12.5)n−1−1100n−11(n−1)K150n−1−1100n−1∴t82.5t50=1(n−1)k100n−1−(12.5)n−1(100)n−1.(12.5)n−11(n−1)k100n−1−50n−1100n−1.50n−1=12.5n−18n−112.5n−150n−1(2n−1−1)50n−1=8n−1−12n−1−1