Final answer:
To evaluate sin 2y, we first find the value of y using the given information. Then, we use the double-angle identity to calculate sin 2y.
Step-by-step explanation:
To evaluate the expression sin 2y, we need to find the value of y first. Given that sec y = 5/4, we can use the identity sec^2 y - 1 = tan^2 y to find tan y. Since sec y = 5/4, we have (5/4)^2 - 1 = tan^2 y. Solving this equation gives us tan y = 9/16. Now, to find sin 2y, we can use the double-angle identity sin 2y = 2sin y cos y. Since we know sin y = 1/3, we can substitute these values into the formula to get sin 2y = 2(1/3)(√(1 - (1/3)^2)). Solving this expression gives us the final answer of sin 2y ≈ 0.595.