Final answer:
To find Joel's age, set up an equation using the mean of their ages. Solve the equation to find x, and then find Joel's age.
Step-by-step explanation:
To find Joel's age, we need to represent the ages of Sunita, Beth, and Joel in terms of x. Let's say Sunita's age is x years. Beth is one year younger than Sunita, so Beth's age is (x - 1) years. Joel is double Sunita's age, so Joel's age is 2x years.
The mean of their ages is 5, so we can set up the equation (x + (x - 1) + 2x)/3 = 5. Simplifying this equation, we get 4x - 1 = 15. Solving for x, we find that x = 4.
Since Joel's age is 2x, Joel's age is 2(4) = 8 years.