Class 10
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Mathematics
Probability
NCERT Solutions
NCERT Solutions
Probability
25 Solutions
Q1
EXERCISE 14.1
Complete the following statements:
(i)
Probability of an event E + Probability of the event 'not E ' = _____ .
(ii)
The probability of an event that cannot happen is _____ . Such an event is called _____ .
(iii)
The probability of an event that is certain to happen is _____ . Such an event is called _____ .
(iv)
The sum of the probabilities of all the elementary events of an experiment is _____ .
(v)
The probability of an event is greater than or equal to _____ and less than or equal to _____ .
Q2
EXERCISE 14.1
Which of the following experiments have equally likely outcomes? Explain.
(i)
A driver attempts to start a car. The car starts or does not start.
(ii)
A player attempts to shoot a basketball. She/he shoots or misses the shot.
(iii)
A trial is made to answer a true-false question. The answer is right or wrong.
(iv)
A baby is born. It is a boy or a girl.
Q3
EXERCISE 14.1
Why is tossing a coin considered to be a fair way of deciding which team should get the ball at the beginning of a football game?
Q4
EXERCISE 14.1
Which of the following cannot be the probability of an event?
(A)
2
3
\frac{2}{3}
3
2
(B) -1.5
(C) 15%
(D) 0.7
Q5
EXERCISE 14.1
If
P
(
E
)
=
0.05
P(E) = 0.05
P
(
E
)
=
0.05
, what is the probability of 'not E'?
Q6
EXERCISE 14.1
A bag contains lemon flavoured candies only. Malini takes out one candy without looking into the bag. What is the probability that she takes out
(i)
an orange flavoured candy?
(ii)
a lemon flavoured candy?
Q7
EXERCISE 14.1
It is given that in a group of 3 students, the probability of 2 students not having the same birthday is 0.992. What is the probability that the 2 students have the same birthday?
Q8
EXERCISE 14.1
A bag contains 3 red balls and 5 black balls. A ball is drawn at random from the bag. What is the probability that the ball drawn is (i) red ? (ii) not red?
Q9
EXERCISE 14.1
A box contains 5 red marbles, 8 white marbles and 4 green marbles. One marble is taken out of the box at random. What is the probability that the marble taken out will be
(i)
red ?
(ii)
white ?
(iii)
not green?
Q10
EXERCISE 14.1
A piggy bank contains hundred 50 p coins, fifty ₹ 1 coins, twenty ₹ 2 coins and ten ₹ 5 coins. If it is equally likely that one of the coins will fall out when the bank is turned upside down, what is the probability that the coin (i) will be a 50 p coin ? (ii) will not be a ₹ 5 coin?
Q11
EXERCISE 14.1
Gopi buys a fish from a shop for his aquarium. The shopkeeper takes out one fish at random from a tank containing 5 male fish and 8 female fish. What is the probability that the fish taken out is a male fish?
Q12
EXERCISE 14.1
A game of chance consists of spinning an arrow which comes to rest pointing at one of the numbers 1, 2, 3, 4, 5, 6, 7, 8, and these are equally likely outcomes. What is the probability that it will point at
(i)
8 ?
(ii)
an odd number?
(iii)
a number greater than 2 ?
(iv)
a number less than 9 ?
Q13
EXERCISE 14.1
A die is thrown once. Find the probability of getting
(i)
a prime number;
(ii)
a number lying between 2 and 6;
(iii)
an odd number.
Q14
EXERCISE 14.1
One card is drawn from a well-shuffled deck of 52 cards. Find the probability of getting
(i)
a king of red colour
(ii)
a face card
(iii)
a red face card
(iv)
the jack of hearts
(v)
a spade
(vi)
the queen of diamonds
Q15
EXERCISE 14.1
Five cards - the ten, jack, queen, king and ace of diamonds, are well-shuffled with their face downwards. One card is then picked up at random.
(i)
What is the probability that the card is the queen?
(ii)
If the queen is drawn and put aside, what is the probability that the second card picked up is (a) an ace? (b) a queen?
Q16
EXERCISE 14.1
12 defective pens are accidentally mixed with 132 good ones. It is not possible to just look at a pen and tell whether or not it is defective. One pen is taken out at random from this lot. Determine the probability that the pen taken out is a good one.
Q17
EXERCISE 14.1
(i)
A lot of 20 bulbs contain 4 defective ones. One bulb is drawn at random from the lot. What is the probability that this bulb is defective?
(ii)
Suppose the bulb drawn in (i) is not defective and is not replaced. Now one bulb is drawn at random from the rest. What is the probability that this bulb is not defective?
Q18
EXERCISE 14.1
A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, find the probability that it bears (i) a two-digit number (ii) a perfect square number (iii) a number divisible by 5.
Q19
EXERCISE 14.1
A child has a die whose six faces show the letters as given below: A B C D E A The die is thrown once. What is the probability of getting (i) A? (ii) D?
Q20
EXERCISE 14.1
Suppose you drop a die at random on the rectangular region shown in Fig. 14.6. What is the probability that it will land inside the circle with diameter 1 m ? (The figure shows a rectangle with length 3 m and breadth 2 m, and a circle with diameter 1 m inside it).
Q21
EXERCISE 14.1
A lot consists of 144 ball pens of which 20 are defective and the others are good. Nuri will buy a pen if it is good, but will not buy if it is defective. The shopkeeper draws one pen at random and gives it to her. What is the probability that
(i)
She will buy it?
(ii)
She will not buy it?
Q22
EXERCISE 14.1
Refer to Example 13. (i) Complete the following table:
Event: 'Sum on 2 dice'
2
3
4
5
6
7
8
9
10
11
12
Probability
1
36
\frac{1}{36}
36
1
5
36
\frac{5}{36}
36
5
1
36
\frac{1}{36}
36
1
(ii) A student argues that 'there are 11 possible outcomes 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12. Therefore, each of them has a probability
1
11
\frac{1}{11}
11
1
. Do you agree with this argument? Justify your answer.
Q23
EXERCISE 14.1
A game consists of tossing a one rupee coin 3 times and noting its outcome each time. Hanif wins if all the tosses give the same result i.e., three heads or three tails, and loses otherwise. Calculate the probability that Hanif will lose the game.
Q24
EXERCISE 14.1
A die is thrown twice. What is the probability that
(i)
5 will not come up either time?
(ii)
5 will come up at least once? [Hint : Throwing a die twice and throwing two dice simultaneously are treated as the same experiment]
Q25
EXERCISE 14.1
Which of the following arguments are correct and which are not correct? Give reasons for your answer.
(i)
If two coins are tossed simultaneously there are three possible outcomes - two heads, two tails or one of each. Therefore, for each of these outcomes, the probability is
1
3
\frac{1}{3}
3
1
.
(ii)
If a die is thrown, there are two possible outcomes - an odd number or an even number. Therefore, the probability of getting an odd number is
1
2
\frac{1}{2}
2
1
.
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