Advertisements
Advertisements
प्रश्न
Suppose error involved in making a certain measurement is continuous r.v. X with p.d.f.
f (x) = k `(4 – x^2)`, for –2 ≤ x ≤ 2 and = 0 otherwise.
P (–0·5 < x or x > 0·5)
Advertisements
उत्तर
Since, f is the p.d.f. of X,
` int_(-∞)^∞ f (x) dx` = 1
∴ ` int_(-∞)^(-2) f (x) dx` +` int_(-2)^(2) f (x) dx` + `int_2^∞f(x) dx = 1`
= 0 + ` int_(-2)^(2) k (4 -x^2) dx + 0 = 1`
∴ k ` int_(-2)^2 (4 -x^2) dx + 0 = 1`
∴ k` [ 4x - x^3/3]_-2^2` = 1
∴ k `[(8-8/3)-(-8+8/3)]`= 1
∴ k`(16/3+16/3)` = 1
∴ k`(32/3)` = 1
∴ k = `3/32`
P (–0·5 < x or x > 0·5)
= P (x < –0·5) + P (x > – 0·5)
= `int_(-∞)^-0.5f (x) dx + int_(0.5)^∞f (x) dx`
=` int_(-∞)^-2 f (x) dx + int_(-2)^-0.5 f (x) dx +int_(0.5)^2f (x) dx + int_(2)^∞ f (x) dx`
= 0+` int_(-2)^(-1/2) k (4 -x^2) dx+ int_(1/2)^2 k (4 -x^2) dx` + 0
= ` k int_(-2)^(-1/2) (4 -x^2) dx+ k int_(1/2)^2 (4 -x^2) dx`
= `3/32[4x-(x^3)/3]_-2^(-1/2)+3/32[4x-(x^3)/3]_(1/2)^2` .......[∵ k =`3/32`]
= `3/32[(-2+1/24)-(-8+8/3)] + 3/32[(8-8/3)-(2-1/24)]`
= `3/32((-47)/24+16/3)+ 3/32(16/3-47/24)`
= `3/32((-47)/24+16/3+16/3-47/24)`
= `3/32((-47+128+128 -47)/24)`
= `3/32(162/24) = 81/128`
= 0.6328
Alternative Method :
P (x< – 0·5 or x > 0·5)
= 1 -P( - 0.5 ≤ x ≤ 0.5)
= 1 -` int_(-0.5)^0.5 f (x) dx `
= 1 - ` int_(-1/2)^(1/2) k (4 - x^2) dx`
= 1 - k ` int_(-1/2)^(1/2) (4 - x^2) dx`
= `1-3/32[4x-x^3/3]_(-1/2)^(1/2)` ......[∵ k = `3/32`]
= `1 - 3/32[(2-1/24)-(-2+1/24)]`
= `1 - 3/32(2-1/24+2-1/24)`
= `1 - 3/32(4-1/12)`
= `1 - 3/32 xx 47/12`
= `1 - 47/128`
= `(128-47)/128`
= `81/128`
= 0.6328
संबंधित प्रश्न
Suppose error involved in making a certain measurement is continuous r.v. X with p.d.f.
f (x) = k `(4 – x^2 )`, for –2 ≤ x ≤ 2 and = 0 otherwise.
P(x > 0)
The following is the p.d.f. of continuous r.v.
f (x) = `x/8`, for 0 < x < 4 and = 0 otherwise.
Find expression for c.d.f. of X
The following is the p.d.f. of continuous r.v.
f (x) = `x/8` , for 0 < x < 4 and = 0 otherwise.
Find F(x) at x = 0·5 , 1.7 and 5
Given the p.d.f. of a continuous r.v. X , f (x) = `x^2/3` ,for –1 < x < 2 and = 0 otherwise
Determine c.d.f. of X hence find
P( x < 1)
Given the p.d.f. of a continuous r.v. X ,
f (x) = `x^2 /3` , for –1 < x < 2 and = 0 otherwise
Determine c.d.f. of X hence find P( x < –2)
Given the p.d.f. of a continuous r.v. X ,
f (x) = `x^2/ 3` , for –1 < x < 2 and = 0 otherwise
Determine c.d.f. of X hence find P( X > 0)
The p.m.f. of a r.v. X is given by P (X = x) =`("" ^5 C_x ) /2^5` , for x = 0, 1, 2, 3, 4, 5 and = 0, otherwise.
Then show that P (X ≤ 2) = P (X ≥ 3).
Solve the following problem :
A player tosses two coins. He wins ₹ 10 if 2 heads appear, ₹ 5 if 1 head appears, and ₹ 2 if no head appears. Find the expected value and variance of winning amount.
It is felt that error in measurement of reaction temperature (in celsius) in an experiment is a continuous r.v. with p.d.f.
f(x) = `{(x^3/(64), "for" 0 ≤ x ≤ 4),(0, "otherwise."):}`
Find P(0 < X ≤ 1).
F(x) is c.d.f. of discrete r.v. X whose p.m.f. is given by P(x) = `"k"^4C_x` , for x = 0, 1, 2, 3, 4 and P(x) = 0 otherwise then F(5) = _______
Solve the following problem :
Identify the random variable as discrete or continuous in each of the following. Identify its range if it is discrete.
Twelve of 20 white rats available for an experiment are male. A scientist randomly selects 5 rats and counts the number of female rats among them.
c.d.f. of a discrete random variable X is
A coin is tossed 10 times. The probability of getting exactly six heads is ______.
A random variable X has the following probability distribution:
| X = x | 0 | 1 | 2 | 3 |
| P (X = x) | `1/10` | `1/2` | `1/5` | k |
Then the value of k is
Out of 100 people selected at random, 10 have common cold. If five persons selected at random from the group, then the probability that at most one person will have common cold is ______.
A six sided die is marked ‘1’ on one face, ‘3’ on two of its faces, and ‘5’ on remaining three faces. The die is thrown twice. If X denotes the total score in two throws, find the cumulative distribution function
A six sided die is marked ‘1’ on one face, ‘3’ on two of its faces, and ‘5’ on remaining three faces. The die is thrown twice. If X denotes the total score in two throws, find P(X ≥ 6)
Suppose a discrete random variable can only take the values 0, 1, and 2. The probability mass function is defined by
`f(x) = {{:((x^2 + 1)/k"," "for" x = 0"," 1"," 2),(0"," "otherwise"):}`
Find the value of k
A random variable X has the following probability mass function.
| x | 1 | 2 | 3 | 4 | 5 |
| F(x) | k2 | 2k2 | 3k2 | 2k | 3k |
Find P(X > 3)
Choose the correct alternative:
Two coins are to be flipped. The first coin will land on heads with probability 0.6, the second with Probability 0.5. Assume that the results of the flips are independent and let X equal the total number of heads that result. The value of E[X] is
Choose the correct alternative:
Suppose that X takes on one of the values 0, 1 and 2. If for some constant k, P(X = i) = kP(X = i – 1) for i = 1, 2 and P(X = 0) = `1/7`. Then the value of k is
Choose the correct alternative:
The probability mass function of a random variable is defined as:
| x | – 2 | – 1 | 0 | 1 | 2 |
| f(x) | k | 2k | 3k | 4k | 5k |
Then E(X ) is equal to:
The p.m.f. of a random variable X is
P(x) = `(5 - x)/10`, x = 1, 2, 3, 4
= 0, otherwise
The value of E(X) is ______
A bag contains 6 white and 4 black balls. Two balls are drawn at random. The probability that they are of the same colour is ______.
If the c.d.f (cumulative distribution function) is given by F(x) = `(x - 25)/10`, then P(27 ≤ x ≤ 33) = ______.
For a random variable X, if Var (X) = 5 and E (X2) = 21, the value of E (X) is ______
A random variable X has the following probability distribution:
| X | 1 | 2 | 3 | 4 |
| P(X) | `1/3` | `2/9` | `1/3` | `1/9` |
1hen, the mean of this distribution is ______
X is a continuous random variable with a probability density function
f(x) = `{{:(x^2/4 + k; 0 ≤ x ≤ 2),(0; "otherwise"):}`
The value of k is equal to ______
The probability distribution of a random variable X is given below. If its mean is 4.2, then the values of a and bar respectively
| X = x | 1 | 2 | 3 | 4 | 5 | 6 |
| P(X = x) | a | a | a | b | b | 0.3 |
The probability distribution of a random variable X is given below.
| X = k | 0 | 1 | 2 | 3 | 4 |
| P(X = k) | 0.1 | 0.4 | 0.3 | 0.2 | 0 |
The variance of X is ______
The c.d.f. of a discrete r.v. x is
| x | 0 | 1 | 2 | 3 | 4 | 5 |
| F(x) | 0.16 | 0.41 | 0.56 | 0.70 | 0.91 | 1.00 |
Then P(1 < x ≤ 4) = ______
The c.d.f. of a discrete r.v. X is
| X = x | -4 | -2 | -1 | 0 | 2 | 4 | 6 | 8 |
| F(x) | 0.2 | 0.4 | 0.55 | 0.6 | 0.75 | 0.80 | 0.95 | 1 |
Then P(X ≤ 4|X > -1) = ?
The p.d.f. of a continuous random variable X is
f(x) = 0.1 x, 0 < x < 5
= 0, otherwise
Then the value of P(X > 3) is ______
A random variable X has the following probability distribution:
| X = xi | 1 | 2 | 3 | 4 |
| P(X = xi) | 0.2 | 0.15 | 0.3 | 0.35 |
The mean and the variance are respectively ______.
Two cards are randomly drawn, with replacement. from a well shuffled deck of 52 playing cards. Find the probability distribution of the number of aces drawn.
A coin is tossed three times. If X denotes the absolute difference between the number of heads and the number of tails then P(X = 1) = ______.
At random variable X – B(n, p), if values of mean and variance of X are 18 and 12 respectively, then total number of possible values of X are ______.
If f(x) = `k/2^x` is a probability distribution of a random variable X that can take on the values x = 0, 1, 2, 3, 4. Then, k is equal to ______.
Find the probability of getting the sum as a perfect square number when two dice are thrown together.
