Bright Bulb light bulb company is planning a study to assess the average life expectancy of their light bulbs. They know the standard deviation is σ = 400 hours. They want a 95% confidence interval with a margin of error of 50 hours. What sample size do they need?

Sample size = 246 .

Step-by-step explanation:

We are given that Bright Bulb light bulb company is planning a study to assess the average life expectancy of their light bulbs. For this they know;

Standard deviation, = 400 hours         Confidence interval = 95%

Margin of error = 50 hours

We know that Margin of error formula is given by;

    Margin of Error =   where = 5%

                   50       =  1.96 *  

                       =   = 15.68

                      n  =   = 245.86 ≈ 246

So, sample size needed will be 246 bulbs.

∠lno ≅ ∠lnm

∠oln ≅ ∠mln

step-by-step explanation:

given   that triangle lno is congruent to triangle lnm.

we have to fill up the blanks in the given question.

according to above order of congruency   kept in mind we can say that

∠lno ≅ ∠lnm

∠oln ≅ ∠mln

ln ≅ ln due to common in both.

hence, by sas congruency,

the side angle side rule   states that if two sides and the included angle of one triangle are congruent to another triangle, then these two triangles are congruent.