Advertisements
Advertisements
प्रश्न
People’s monthly electric bills in Chennai are normally distributed with a mean of ₹ 225 and a standard deviation of ₹ 55. Those people spend a lot of time online. In a group of 500 customers, how many would we expect to have a bill that is ₹ 100 or less?
Advertisements
उत्तर
Let X be a normally distributed variable with a mean of ₹ 225 and a standard deviation of ₹ 55
Here µ = 225 and σ = 55
The standard normal variate z = `(x - mu)/sigma = (x - 225)/55`
P(a bill have ₹ 100 or less) = P(X ≤ 100)
When x = 100
z = `(100 - 25)/55`
= `(-125)/55`
= – 2.27
P(X ≤ 100) = P(Z < – 2.27)
P(z < – 2.27) = P(`-oo` < z < 0) – P(– 2.27 < z < 0)
= 0.5 – P(0 < z < 2.27)
= 0.5 – 04884
= 0.0116
APPEARS IN
संबंधित प्रश्न
In a particular university 40% of the students are having newspaper reading habit. Nine university students are selected to find their views on reading habit. Find the probability that all those selected have newspaper reading habit
Determine the binomial distribution for which the mean is 4 and variance 3. Also find P(X=15)
The average number of phone calls per minute into the switchboard of a company between 10.00 am and 2.30 pm is 2.5. Find the probability that during one particular minute there will be no phone at all
In a distribution 30% of the items are under 50 and 10% are over 86. Find the mean and standard deviation of the distribution
If the heights of 500 students are normally distributed with mean 68.0 inches and standard deviation 3.0 inches, how many students have height less than or equal to 64 inches
Choose the correct alternative:
Cape town is estimated to have 21% of homes whose owners subscribe to the satellite service, DSTV. If a random sample of your home is taken, what is the probability that all four homes subscribe to DSTV?
Choose the correct alternative:
Let z be a standard normal variable. If the area to the right of z is 0.8413, then the value of z must be:
Choose the correct alternative:
If P(Z > z) = 0.8508 what is the value of z (z has a standard normal distribution)?
A manufacturer of metal pistons finds that on the average, 12% of his pistons are rejected because they are either oversize or undersize. What is the probability that a batch of 10 pistons will contain no more than 2 rejects?
A manufacturer of metal pistons finds that on the average, 12% of his pistons are rejected because they are either oversize or undersize. What is the probability that a batch of 10 pistons will contain at least 2 rejects?
