"The average playing time of compact discs in a large collection is 35 minutes, and the standard deviation is 5 minutes. The following are all true or false? (A) Value 1 standard deviation above mean = 40 min.(B) Value 1 standard deviation below mean = 30 min.(C) Value 2 standard deviations above mean = 45 min.(D) Value 2 standard deviations below mean = 25 min.

Answer:All the given statements are trueStep-by-step explanation:Data provided in the question:The average playing time of compact discs in a large collection = 35 minutesThe standard deviation, σ = 5 minutesNow,(A) value of 1 standard deviation above mean = Mean + σ= 35 + 5 = 40 minutesHence, true(B) Value 1 standard deviation below mean = Mean - σ= 35 - 5 = 30 minutesHence, true(C) Value 2 standard deviations above mean = Mean + 2σ = 35 + 2 × 5= 45 minutesHence, true(D)  Value 2 standard deviations below mean = Mean - 2σ = 35 - 2 × 5= 25 minutesHence, trueTherefore,All the given statements are true