Question

1/4 is the arithmetic mean of 1/5 and what number?

a) 1/10
b) 1/3
c) 1/2
d) 1/8

Answer 1

The arithmetic mean of 1/5 and the number in question is 1/4. By setting up and solving the equation (1/5 + x)/2 = 1/4, it is determined that the missing number is 1/3.

Step-by-step explanation:

To find the arithmetic mean of two numbers, you add them together and divide by 2. If 1/4 is the mean of 1/5 and another number, we can set up an equation:
(1/5 + x)/2 = 1/4. Solving for x, we get 2*(1/4) - 1/5 = x. This simplifies to 1/2 - 1/5 = x, which is (5/10 - 2/10) = 3/10, which simplifies to 1/3. Therefore, 1/4 is the arithmetic mean of 1/5 and 1/3.

The correct answer is b) 1/3.