35) Let us assume that a student is chosen from a random
sample of 80 students, out of which 30 have opted for
Maths, 20 opted for Physics, and 10 have opted for both
Maths and Physics. Find the probability that the student
has opted for either Maths or
Physics.
Answers
Solution :
According to the given Question ;
Total number of students → 80 students .
Total number of students opting for Maths → 30 students .
Total number of students opting for Physics → 20 students .
Total number of students opting for both → 10 students .
So , we can say :
Total number of students who opted for only Maths → ( 30 - 10 )
→ 20 students .
Total number of students who opted for only Physics
→ ( 20 - 10 ) students
→ 10 students .
Total number of students who opted for either maths of physics
=> 10 students + 20 students
=> 30 students .
Thus , the required probability becomes ( 30/80) or ⅜ .
This is the answer .
__________________________________
Answer:
the answer is 1/2 (while assuming by default that the students opting for both maths and physics are(common) among those who have either opted for physics or maths i.e a separate section for "both maths and physics" students is NOT set up)
Step-by-step explanation:
total number of students with only maths= 30
total number of students with only physics=20
total number of student with either maths or physics= 30+20=50
BUT
10 students of BOTH MATHS AND PHYSICS are common to them so they need to be excluded;
hence net total number of students with either maths or physics=50-10=40
hence the probability of the students having either maths or physics = 40/80 =1/2=0.5
hope it helps
inayat abbas malla