Alightbulb has a normally distributed light output with mean 5000 end foot-candles and standard deviation of 50 end foot-candles. find a lower specification limit such that

To find the specification limit such that only 0.5% of the bulbs will not exceed this limit we proceed as follows;
From the z-table, a z-score of -2.57 cuts off 0.005 in the left tail; given the formula for z-score
(x-μ)/σ
we shall have:
(x-5000)/50=-2.57
solving for x we get:
x-5000=-128.5
x=-128.5+5000
x=4871.50

The expression has two variables x and y.

Step-by-step explanation:

What is a variable?

A variable is a letter, for instance or , that represents an unknown number.

Given the expression

The given expression has three terms which are x, 4y, and -9.

Here:

The term 'x' is the unknown variable x.The term '4y' has a coefficient (the number next to a variable y) of 4.The term '-6' is a constant.

As we already know that a variable is a letter, for instance x or y, that represents an unknown number. In other words, the values of x, or y are unknown to us.

Thus, the expression has two variables x and y.