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