The blood groups of 30 students of class IX are recorded as follows:

A B O O AB O A O B A O B A O O

A AB O A A O O AB B A O B A B O

A student is selected at random from the class from blood donation, Fin the probability that the blood group of the student chosen is:
(i) A
(ii) B
(iii) AB
(iv) O

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Solution

The total number of trials is 30.

Remember the empirical or experimental or observed frequency approach to probability.

If n be the total number of trials of an experiment and A is an event associated to it such that A happens in m-trials. Then the empirical probability of happening of event A is denoted byand is given by

(i) Let A₁ be the event that the blood group of a chosen student is A.

The number of times A₁ happens is 9.

Therefore, we have

(iii) Let A₂ be the event that the blood group of a chosen student is B.

The number of times A₂ happens is 6.

Therefore, we have

(iii) Let A₃ be the event that the blood group of a chosen student is AB.

The number of times A₃ happens is 3.

Therefore, we have

(iv) Let A₄ be the event that the blood group of a chosen student is O.

The number of times A₄ happens is 12.

Therefore, we have

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Similar questions

The blood groups of 30 students of class IX are recorded as follows:

$\begin{matrix} A, & B, & O, & O, & A B, & O, & A, & O, & B, & A, & O, & B, & A, & O, & O, A, & A B, & O, & A, & A, & O, & O, & A B, & B, & A, & O, & B, & A, & B, & O, \end{matrix}$

A student is selected at random from the class from blood donation. Find the probability that the blood group of the students chosen is:

(i) A (ii) B (iii) C (iv) O

Q. In a medical examination of students of a class, the following blood groups are recorded.

\begin{matrix} Blood group & A + & A B - & B - & O + Number of & 10 & 13 & 12 & 5 students \end{matrix}

A student is selected at random from the class. The probability that he/she has blood group

B -

is:

Q. The blood groups of 30 students of a class were recorded as under:

Blood Group	A	B	AB	O
No. of students	9	11	4	6

If a student of this class is chosen at random, what is the probability that the chosen student has blood group
(i) O?
(ii) A?
(iii) AB?

Question 27
In a medical examination of students of a class, the following blood groups are recorded.

$\begin{matrix} Blood group & A & A B & B & O Number of & 10 & 13 & 12 & 5 students \end{matrix}$

A student is selected at random from the class. The probability that he/she has blood group B is:

A) $\frac{1}{4}$
B) $\frac{13}{40}$
C) $\frac{3}{10}$
D) $\frac{1}{8}$

The following table shows the blood groups of 40 students of a class.

$\begin{matrix} Blood group & A & B & O & A B Number of students & 11 & 9 & 14 & 6 \end{matrix}$

One student of the class is chosen at random. What is the probability that the chosen studet has blood group (i) O? (ii) AB?

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The blood groups of 30 students of class IX are recorded as follows: A B O O AB O A O B A O B A O O A AB O A A O O AB B A O B A B O A student is selected at random from the class from blood donation, Fin the probability that the blood group of the student chosen is: (i) A (ii) B (iii) AB (iv) O

The blood groups of 30 students of class IX are recorded as follows:

A B O O AB O A O B A O B A O O

A AB O A A O O AB B A O B A B O

A student is selected at random from the class from blood donation, Fin the probability that the blood group of the student chosen is:
(i) A
(ii) B
(iii) AB
(iv) O