Posted by Joy on Sunday, January 22, 2012 at 4:14pm.
Shown below are the data giving the length of life of lights in an underground tunnel.
9.0 months 7.0 months
8.2 months 8.3 months
7.8 months 8.1 months
7.5 months 7.6 months
9.1 months 7.4 months
I calculated the standard deviation to be about 0.679.
Estimate the probability that a random chosen light will last as long as 7 months after installation. Assume the data to be described by a normal distribution.
Can anyone help me with the process I would use to calculate the answer? Thanks!
- Statistics - MathGuru, Sunday, January 22, 2012 at 7:31pm
Use z-scores. Find the mean. You have already calculated standard deviation.
Formula for z-scores is the following:
z = (x - mean)/sd
Use 7 for x. Calculate z-score. Determine the probability using a z-distribution table.
- Statistics - Joy, Sunday, January 22, 2012 at 7:42pm
Thanks for the insight!
So I've calculated the z-score to be about -1.47, or about -1.5. Looking at a z-distribution table, I see on the left a column for z-scores and I see -1.5 there, but there are many values corresponding on the right?
Do you know how I know which one to use?
- Statistics - Joy, Sunday, January 22, 2012 at 7:58pm
Never mind- I've figured it out, THANK YOU MathGuru!
Answer This Question
More Related Questions
- science - Shown below are the data giving the length of life of lights in an ...
- Math - Caroline saves $45 in 4 months. At this rate, how long will it take her ...
- Statistics - . A certain company makes 12-volt car batteries. After many years ...
- math - A person takes out a monthly installment loan of $2000 with an annual ...
- Statistics - A certain company makes 12-volt car batteries. After many years of ...
- Algebra - On her birthday today, Ali's age in months is twice her age in years ...
- math - John's account of 98.50 has been delinquent for 3 months. After 90 days ...
- Financial Mathematics - The Z Corporation needs $180,000 in 60 months. If they ...
- human growth and development - According to the Bayley Scales of Infant ...
- stats - 2. The average age of a child in kindergarten is 66 months. The standard...