单选题
What is the average (arithmetic mean) of 330, 360, and 390?
A. 360 B. 3177 C. 310 + 320 + 330
D. 327 + 357 + 387 E. 329 + 359 + 389
A. 360 B. 3177 C. 310 + 320 + 330
D. 327 + 357 + 387 E. 329 + 359 + 389
【正确答案】
E
【答案解析】To find the average of three numbers, divide their sum by 3: 
Now use the distributive law and divide each term in the numerator by 3: 
Now use the distributive law and divide each term in the numerator by 3: