The average (arithmetic means) of t and y is 15, and the average of w and x 15. What is the average of t, w, x, and y?
(A) 7.5
(B) 15
(C) 22.5
(D) 30
(E) 60
t + y = 15
t + y / 2 = 15
2 * t + y / 2 = 15 *2
t + y = 30
w + x = 15
w + x / 2 = 15
2 * w + x / 2 = 15 * 2
w + x = 30
t + y + w + x / 4
30 + 30 / 4
60 / 4
15
To find the average of t, w, x, and y, we need to first find the values of t, y, w, and x.
From the given information, we know that the average of t and y is 15, which means their sum is 15 * 2 = 30. So, we have t + y = 30.
Similarly, the average of w and x is also 15, so their sum is 15 * 2 = 30. So, we have w + x = 30.
To find the average of t, w, x, and y, we need to find their sum and divide it by 4 (since there are 4 numbers).
Adding the two equations we obtained earlier, we have (t + y) + (w + x) = 30 + 30, which simplifies to t + y + w + x = 60.
Now, we can find the average by dividing the sum by 4: (t + y + w + x)/4 = 60/4 = 15.
Therefore, the average of t, w, x, and y is 15.
Hence, the answer is (B) 15.