# Lifespan

The lifetime of a light bulb is a random variable with a normal distribution of x = 300 hours, σ = 35 hours.

a) What is the probability that a randomly selected light bulb will have a lifespan of more than 320 hours?

b) Up to what value of L hours can the lamp life be expected to last longer than L hours with a probability of 0.25?

a) What is the probability that a randomly selected light bulb will have a lifespan of more than 320 hours?

b) Up to what value of L hours can the lamp life be expected to last longer than L hours with a probability of 0.25?

**Correct result:****Showing 0 comments:**

Tips to related online calculators

Looking for help with calculating arithmetic mean?

Looking for a statistical calculator?

Looking for a standard deviation calculator?

Would you like to compute count of combinations?

Looking for a statistical calculator?

Looking for a standard deviation calculator?

Would you like to compute count of combinations?

#### You need to know the following knowledge to solve this word math problem:

We encourage you to watch this tutorial video on this math problem: video1

## Next similar math problems:

- IQ Intelligence quotient

Intelligence quotient (IQ) is a standardized score used as the output of standardized intelligence psychological tests to quantify a person's intelligence with the rest of the population (respectively to a given group). Intelligence has an approximately n - Normal Distribution

At one college, GPA's are normally distributed with a mean of 3.1 and a standard deviation of 0.4. What percentage of students at the college have a GPA between 2.7 and 3.5? - Ball bearings

One bearing is selected from the shipment of ball bearings. It is known from previous deliveries that the inner bearing radius can be considered as a normal distribution of N (µ = 0.400, σ2 = 25.10^−6). Calculate the probability that the selected radius w - Statistics quiz

Fill in the missing word 1. in a data set, the mean, median and mode are measured of ________________ 2. "The manipulation of variables under controlled conditions"is the data collection method known as______________ 3. in a normal distribution, the area - Probability of failures

In certain productions, the probability of failures is 0.01. Calculate the probability that there will be more than 1 failure among the 100 selected products if we return the selected products to the file after the check. - Stoaches

Stoaches are fictional creatures distantly related to bigfoot and yeti. Stoach weights are normally distributed, with mean 904g and standard deviation 104g. State the probability that the sample mean of a random sample of 36 stoach weights exceeds 943g. ( - Rectangle

In rectangle with sides, 6 and 3 mark the diagonal. What is the probability that a randomly selected point within the rectangle is closer to the diagonal than to any side of the rectangle? - SD - mean

Mean is 10 and standard deviation is 3.5. If the data set contains 40 data values, approximately how many of the data values will fall within the range 6.5 to 13.5? - Probability of malaria

A survey carried out at a certain hospital indicates that the probability that a patient tested positive for malaria is 0.6. What is the probability that two patients selected at random (i) one is negative while the other tested positive? (i) both patient - Assembly time

The assembly time for the toy follows a normal distribution with a mean of 75 minutes and a standard deviation of 9 minutes. The company closes at 5 pm every day. If one starts assembling at 4 pm what is the probability that he will finish before the comp - Alopecia

Medical literature indicates that 45% of men suffer from alopecia. For random sample of 8 men, calculate the probability that: (a) exactly four men suffer from alopecia. (b) at most two men suffer from alopecia. - The accompanying

The accompanying table gives the probability distribution of the number of courses randomly selected student has registered Number of courses 1 2 3 4 5 6 7 Probability 0.02 0.03 0.1 0.3 0.4 - 0.01 respectively. a) Find the probability of a student registe - Chambers

The decision-making committee consists of three people. In order for the commission's decision to be valid, at least two members must vote in the same way. It is not possible not to vote in the commission, everyone only votes yes or no. We assume that the - Records

Records indicate 90% error-free. If 8 records are randomly selected, what is the probability that at least 2 records have no errors? - Complaints

The table is given: days complaints 0-4 2 5-9 4 10-14 8 15-19 6 20-24 4 25-29 3 30-34 3 1.1 What percentage of complaints were resolved within 2weeks? 1.2 calculate the mean number of days to resolve these complaints. 1.3 calculate the modal number of day - Throw

We throw 2 times with 2 dices. What is the probability that the first roll will fall more than sum of 9 and the second throw have sum 3 or does not have the sum 4? - Doctor 2

A doctor noted the Diastolic Blood Pressure (DBP) of a large number of patients. Later, he scrambled the data to keep the privacy of his patients. Based on the scrambled dataset, he finds that the lower inner fence is equal to 50 and the upper inner fence