Q1. Triangles are formed by joining the vertices of an octagon. Any one of those triangle is selected at random. What is the probability that the selected triangle has no side common with the octagon? Q2. In a class 40% of the students offered physics, 20% offered chemistry and 5% offered both. If a student is selected at random , what is the probability that he has offered physics or chemistry only. Q3. Find the probability that a year chosen at random has 53 Mondays? Q4. A and B plays a game where each is asked to select a number from 1 to 25. If the two numbers match, both of them win a prize. The probability that they will not win a prize in a single trial is Q5. Seven digits from the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 are written in random order. The probability that this seven digit numbers is divisible by 9 is : Q6. A fair coin is tossed repeatedly. If tail appears on first four tosses, then the probability of head appearing on the fifth toss equals: Q7. What is the probability that a 4 digit number of the type abcd(a, b, c, d are all different is a multiple of 11? Q8. There are 5 envelopes corresponding to 5 letters. If the letters are placed in the envelopes in the random, what is the probability that all the letters are not placed in the right envelopes ? __________________
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Q1. b. 2/7
Q4. d. 24/25
Q7. a. 0.142
Sugandha Chatterjee
Q1. Triangles are formed by joining the vertices of an octagon. Any one of those triangle is selected at random. What is the probability that the selected triangle has no side common with the octagon?
a. 3/7
b. 2/7
c. 1/7
d. 5/7
ANS : I THINK THE OPTIONS ARFE WRONG IF THE TRIANGLES ARE MADE VTH VERTICES OF OCTAGON HOW CAN THEY NT HAVE ANY SIDE COMMON VTH THEM..!!!
Q2. In a class 40% of the students offered physics, 20% offered chemistry and 5% offered both. If a student is selected at random , what is the probability that he has offered physics or chemistry only.
a. 45%
b. 55%
c. 36%
d. None of these
ANS: B, 40+20-5=55.
Q3. Find the probability that a year chosen at random has 53 Mondays?
a. 5/28
b. 3/28
c. 1/28
d. 3/28
ANS: YET AGIN NO IDEA.. GUYS VTH ANS DO POST
Q4. A and B plays a game where each is asked to select a number from 1 to 25. If the two numbers match, both of them win a prize. The probability that they will not win a prize in a single trial is
a. 21/24
b. 27/28
c. 29/30
d. 24/25
ANS: D , OBVIOUSLY I DNT FEEL THERE IS NEED OF EXPLANATION.!
Q5. Seven digits from the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 are written in random order. The probability that this seven digit numbers is divisible by 9 is :
a. 7/9
b. 1/9
c. 2/9!
d. 4/9
ANS: C , CHECKING DIVISIBILITY TEST OF 9 , 7N 8 CANT B IN THE SET , ALSO ARRANGEMENT IS POSS IN 9! WAYS THE ONLY OPTION.!!
Q6. A fair coin is tossed repeatedly. If tail appears on first four tosses, then the probability of head appearing on the fifth toss equals:
a. 5/12
b. 1/2
c. 5/6
d. 1/6
ANS B, IF THE COIN IS FAIR , THE RESULT OF EACH TOSS ARE INDEPENDENT EVENTS..!
Q7. What is the probability that a 4 digit number of the type abcd(a, b, c, d are all different is a multiple of 11?
a. 0.142
b. 0.048
c. 0.072
d. 0.091
SORRY NO IDEA IF NE1 DO HAVE THE ANS KINDLY TO POST IT..!!
Q8. There are 5 envelopes corresponding to 5 letters. If the letters are placed in the envelopes in the random, what is the probability that all the letters are not placed in the right envelopes ?
a. 119/120
b. 59/60
c. 23/24
d. 4^5/5^5
ANS: A, AS THERE IS ONLY 1 CHNC THAT THE ARRANGEMENT IS SYSTEMATIC..~~!
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