Suppose that a brand of lightbulb lasts on average 2875 hours with a standard deviation of...
The life expectancy of a particular brand of light bulbs is normally distributed with a mean of 1500 hours and a standard deviation of 75 hours. What is the probability that a bulb will last between 1500 and 1650 hours?
(Sec. 4.3) An average light bulb manufactured at The Lightbulb Company lasts and average of 300 days, with a standard deviation of 50 days. Suppose the lifespan of a light bulb from this company is normally distributed. (a) What is the probability that a light bulb from this company lasts less than 210 days? More than 330 days? (b) What is the probability that a light bulb from this company lasts between 280 and 380 days? (c) How would you...
The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 75 hours. Tests show that the life of the bulb is approximately normally distributed. What is the range of hours that approximately 68% of the bulbs will last?
A brand of lightbulb has an average life of 600 hr, with a standard deviation of 40 hr. The length of life of the bulb can be closely approximated by a normal curve. A warehouse manager buys and installs 10,000 such bulbs. Find the total number that can be expected to last less than 716 hr The total number of bulbs that can be expected to last less than 716 hr is (Round to the nearest whole number as needed.)
A brand of lightbulb has an average life of 600 hr, with a standard deviation of 50 hr. The length of life of the bulb can be closely approximated by a normal curve. A warehouse manager buys and installs 10,000 such bulbs. Find the total number that can be expected to last less than 730 hr. the total number of bulbs that can be expected to last less than 730 hr is ? (Round to the nearest whole number as...
Suppose a brand of light bulbs is normally distributed, with a mean life of 1700 hr and a standard deviation of 150 hr. Find the probability that a light bulb of that brand lasts between 1415 hr and 1910 hr.
13. The lifetime of lightbulbs that are advertised to last for 5000 hours are normally distributed with a mean of 5100 hours and a standard deviation of 100 hours. What is the probability that a bulb lasts longer than the advertised figure? Use three decimals of accuracy in your answer. Probability = 14. The combined math and verbal scores for females taking the SAT-I test are normally distributed with a mean of 998 and a standard deviation of 202 (based...
The life in hours of a certain type of lightbulb is normally distributed with a known standard deviation of 10 hours. A random sample of 15 lightbulbs has a sample mean life of 1000 hours. What would the 99% lower-confidence bound L on the mean life be, rounded to the nearest integer?
The lifetime of lightbulbs that are advertised to last for 6500 hours are normally distributed with a mean of 6700 hours and a standard deviation of 300 hours. What is the probability that a bulb lasts longer than the advertised figure? Probability =
1. A certain type of radio tubes lasts on the average of 2 years with the standard deviation of 0.4 year. Assuming that the radio tubes are normally distributed. Find the probability that given tubes will last less than 1.5 years. Two hundred college freshmen have their grades in the normal distribution with the mean of 2.2 and standard deviation of 0.6. How many of these freshmen have their grades between 2.0 and 2.5 inclusive? Suppose that in an examination,...