PROBABILITY
PRACTICE PROBLEMS
PROBLEM 1
A coin is thrown 3 times .what is the
probability that atleast one head is
obtained?
ANSWER
7/8
PROBLEM 2
Find the probability of getting a
numbered card when a card is drawn
from the pack of 52 cards.
ANSWER
9/13
PROBLEM 3
There are 5 green 7 red balls. Two
balls are selected one by one without
replacement. Find the probability
that first is green and second is red.
ANSWER
35/132
PROBLEM 4
What is the probability of getting a
sum of 7 when two dice are thrown?
ANSWER
1/6
PROBLEM 5
1 card is drawn at random from the
pack of 52 cards. Find the Probability
that it is an honor card.
ANSWER
4/13
PROBLEM 6
1 card is drawn at random from the
pack of 52 cards. Find the Probability
that it is a face card.
ANSWER
3/13
PROBLEM 7
A circle is inscribed in a square. A point
inside the square is randomly selected.
What is the probability that the point is
inside the circle as well?
ANSWER
π/4
PROBLEM 8
A square was inscribed in the circle,
and a point inside the circle was
randomly selected, what is the
probability that it is inside the square?
ANSWER
2/π
PROBLEM 09
A card game is played using only the short deck
shown in the image. What is the probability of
picking either a club or a heart for the first trial and
either a red card or a spade for the second trial
assuming that you return the first card before
proceeding to the second trial.
ANSWER
3/8
PROBLEM 10
A tire manufacturing company encourages its employees to promote a zero-accident environment
by practicing safety measures. However, for the past year, there are 300 recorded accidents. The
data below categorized these accidents according to the shift (morning, mid, and night) when it
happened and the reason of the accident (dangerous conditions and employee error). For instance,
5% of the accidents occurred during morning shift for the reason of dangerous conditions. As an
HR manager, you are tasked to select one incident at random as part of your presentation to
newly-hired employees. What is the probability of choosing an accident due to employee error
given the fact that it happened during the night shift.
ANSWER
0.9375
PROBLEM 11
Given the same information from the previous item,
evaluate the probability of choosing an accident
that happened during the mid shift knowing that
the cause of the accident is due to dangerous
conditions.
ANSWER
46.15%
PROBLEM 12
A draw box contains 4 pink, 5 white and 6 gray balls.
Three balls are drawn at random from the draw box
without returning.The probability that all of them
are pink, is:
ANSWER
0.879%
PROBLEM 13
You pick three colored balls at random successively.
What is the probability that the order is pink, white
and gray if there are 5 pink balls, 6 white balls, and 7
gray balls.
ANSWER
4.289%
PROBLEM 14
A chalk box contains 5 pink chalks and 4 white
chalks. If three items are picked at random,
assuming that you return the chalk after picking
each time, what is the probability that at least 1 of
them is a pink chalk?
ANSWER
91.22%
PROBLEM 15
A coin purse has 3 OLD one-peso coins and 7 NEW
one-peso coins. Suppose you randomly pick a coin
and upon selecting, a dummy silver coin is placed on
the purse as a placeholder for the coin you picked. If a
second coin is picked from the coin purse, what is the
probability that the second coin is an OLD one peso?
ANSWER
27%
PROBLEM 16
The probability of getting a credit in an examination
is 1/3. If three students are selected at random, what
is the probability that at least one of the students get
a credit?
ANSWER
19/27
PROBLEM 17
Box A contains 8 items of which 3 are defective and
box B contains 5 items of which 2 are defective. An
item is drawn at random from each box. What is the
probability that one item is defective and one is not?
ANSWER
19/40