4. The time to complete a standardized exam is approximately normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the 68-95-99.7 rule, what percent of students will complete the exam in under an hour?
(A) \( 68\% \)
(B) \( 32\% \)
(C) \( 16\% \)
(D) \( 5\% \)
(E) \( 1\% \)
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統計: 尚無統計資料
統計: 尚無統計資料