Instruction 7.3 The Lifetimes of a Certain Brand of Light Bulbs Are

question 5

Short Answer

Instruction 7.3
The lifetimes of a certain brand of light bulbs are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours. A random sample of 64 of these light bulbs is taken.
-Referring to Instruction 7.3,what is the probability that the sample mean lifetime is more than 1,550 hours?

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Definitions:

Metric Thread

A standardized thread type used internationally, characterized by its metric dimensions, commonly used in bolts, screws, and nuts.

Internal Thread

The spiral grooves cut inside a hole intended to engage with an external thread, such as on a bolt, allowing for parts to be screwed together.

Plain Bearings

Bearings that operate through sliding motion between the moving surfaces, without rollers or balls, used for simpler mechanisms.

Journal Bearings

Bearings that support a rotating shaft, where the shaft rotates within a lubricated sleeve or shell without rolling elements.