The sum of five positive numbers is equal to 1, and all five positive numbers are greater than 1/5, that is, A > 1/5.

b > 1/5 c > 1/5d > 1/5 e

e> 1/5

a+b+c+d+e > 5×( 1/5)= 1

The sum of these five numbers is greater than 1, which contradicts the known condition that the sum of five positive numbers is equal to 1, so the assumption is not established, so,

At least one of these five positive numbers is less than or equal to 5 of 1.