The life in hours of a thermocouple used in a furnace is known to be approximately normally distributed, with standard deviation σ = 20 hours. a random sample of 15 thermocouples resulted in the following data: 553, 552, 567, 579, 550, 541, 537, 553, 552, 546, 538, 553, 581, 539, 529. we wanted to be 95% confident that the error in estimating the mean life is less than 5 hours. what sample size should we use? round z-value to two decimal places in your intermediate calculations. round your answer up to the nearest whole number.

62 is the minimum sample size needed

Step-by-step explanation:

We know that the population is approximately normally distributed so we will use a z-score for 95% confidence, which is 1.96.  We are given the population standard deviation of σ = 20, and are given that the error should be 5 or less hours.  The fact that it gives us sample data is irrelevant since we are told the population is approximately normally distributed and are given the population standard deviation.

See the attached photo for the calculation of the minimum sample size

you could deduce the conclusion directly using the facts pertaining to the specific situation.

hope this .

1. 180°. the sum of the interior angles of a triangle is 180°, for the equilateral triangle that it has three equals side is 60°+60°+60°=180°.

2. 60°. each interior angle of a equilateral triangle is 60°

3. 120°. the measure of ∠m is 120°, the sum of the angles ∠m and ∠n is equal to 180°. so, in order to find the measure of ∠m, we have ∠m+∠n=180° > ∠m=180°-∠n > ∠m=180°-60°=120°.

4. 360°. the sum of the exterior angles of an equilateral triangle is ∠m+∠r+∠x=120°+120°+120°=360°. the exterior angles of any triangle always add 360°.