4. The blood groups of some students of Class IX were surveyed and rec

1.	4. The blood groups of some students of Class IX were surveyed and recorded as below:Blood GroupABAB0No. of Students1961312If a student is chosen at random, find the probability that he/she has blood group A or AB.
Answer» The blood groups of some students of Class IX were surveyed and recorded as below: Blood Group No. of Students A 19 B 6 AB 13 O 12 TOTAL 50 We have to find, the probability that he/she has blood group A or AB. Solution: Here, Total number of students = 50 Total number if possible OUTCOMES = 50 For blood group A: Number of students having blood A = 19 ∴ P(A) = $\dfrac{Number of favourable outcomes}{All possible outcomes}$ P(A) = $\dfrac{19}{50}$ THUS, the probability that he/she has blood group A is $\dfrac{19}{50}$ . OR: For blood group AB: Number of students having blood AB = 13 ∴ P(AB) = $\dfrac{Number of favourable outcomes}{All possible outcomes}$ P(AB) = $\dfrac{13}{50}$ The probability that he/she has blood group A or AB(A ∪ AB) = P(A) + P(AB) = $\dfrac{19}{50}$ + $\dfrac{13}{50}$ = $\dfrac{32}{50}$ = $\dfrac{16}{25}$ Hence, the probability that he/she has blood group A or AB is" $\dfrac{16}{25}$ ".

4. The blood groups of some students of Class IX were surveyed and recorded as below:Blood GroupABAB0No. of Students1961312If a student is chosen at random, find the probability that he/she has blood group A or AB.

Answer»

The blood groups of some students of Class IX were surveyed and recorded as below:

Blood Group No. of Students

A 19

B 6

AB 13

O 12

TOTAL 50

We have to find, the probability that he/she has blood group A or AB.

Solution:

Here,

Total number of students = 50

Total number if possible OUTCOMES = 50

For blood group A:

Number of students having blood A = 19

∴ P(A) = $\dfrac{Number of favourable outcomes}{All possible outcomes}$

P(A) = $\dfrac{19}{50}$

THUS, the probability that he/she has blood group A is $\dfrac{19}{50}$ .

OR:

For blood group AB:

Number of students having blood AB = 13

∴ P(AB) = $\dfrac{Number of favourable outcomes}{All possible outcomes}$

P(AB) = $\dfrac{13}{50}$

The probability that he/she has blood group A or AB(A ∪ AB)

= P(A) + P(AB)

= $\dfrac{19}{50}$ + $\dfrac{13}{50}$

= $\dfrac{32}{50}$

= $\dfrac{16}{25}$

Hence, the probability that he/she has blood group A or AB is" $\dfrac{16}{25}$ ".