The shortest lifespan will last less than 2.5 years.
What is standard deviation?
The standard deviation is a statistic that expresses how much variance or dispersion there is in a group of numbers. While a high standard deviation suggests that the values are dispersed throughout a wider range, a low standard deviation suggests that the values tend to be close to the established mean.
First, we must utilize the conventional normal table to determine the value for z if 10% of the region (probability) to its left will be present. We can observe that about z = -1.282.
Now, we have to find the value of x, that corresponds to the value of z.
Since,
(x - μ) / σ = z
(x - 3.1) / 0.5 = -1.282
x = 2.459
Hence, the shortest lifespan will last less than 2.5 years.
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