Probability
Ratios
Corresponding
100
The blood group of 60 students of a class recorded as below.
Blood Group
A
B
AB
O
Number of Students
12
20
10
18
A student of the class is selected at random.
(i) What is the probability that the selected student has blood group O?
(ii) What is the probability that the selected student does not have blood group O?
Total number of trials = 60. [Since, there are 60 different students).
Number of students having blood group O = 18.
So, the probability of the student’s blood group being O
100
A and B together have Rs. 1210. If 
of A's amount is equal to 
of B's amount, how much amount does B have?
4A=2B155
A =
2x15
B54
A =3B2
A=3B2
A : B = 3 : 2.
B's share = Rs.1210 x2= Rs. 484.5
100
SU = 35mm UT = 45mm
FE = 36mm
Find DF
DF = 28
200
Out of 300 students in a school, 95 play cricket only, 120 play football only, 80 play volleyball only and 5 play no games. If one student is chosen at random, find the probability that
Total number of trials = 300 (Since there are 300 students all together).
Number of times a cricket player is chosen = 95 (Since 95 students play cricket).
Number of times a football player is chosen = 120.
Number of times a volleyball player is chosen = 80.
Number of times a student is chosen who plays no games = 5.
(i) Therefore, the probability of getting a player who plays volleyball
200
Two numbers are respectively 20% and 50% more than a third number. The ratio of the two numbers is:
Let the third number be x.
Then, first number = 120% of x =120x=6x1005
Second number = 150% of x =150x=3x1002
Ratio of first two numbers =6x:3x= 12x : 15x = 4 : 5.
200
JM = 21 in
JK = 36 in
SP = 35 in
PQ = ?
54 in
300
A coin is thrown 3 times .what is the probability that atleast one head is obtained?
Sample space = [HHH, HHT, HTH, THH, TTH, THT, HTT, TTT]
Total number of ways = 2 × 2 × 2 = 8. Fav. Cases = 7
P (A) = 7/8
OR
P (of getting at least one head) = 1 – P (no head)⇒ 1 – (1/8) = 7/8
300
A sum of money is to be distributed among A, B, C, D in the proportion of 5 : 2 : 4 : 3. If C gets Rs. 1000 more than D, what is B's share?
Let the shares of A, B, C and D be Rs. 5x, Rs. 2x, Rs. 4x and Rs. 3x respectively.
Then, 4x - 3x = 1000
x = 1000.
B's share = Rs. 2x = Rs. (2 x 1000) = Rs. 2000.
300
BC = 24 in
AC = 36 in
NM = 16 in
LN = ?
45 in
400
Find the probability of getting a numbered card when a card is drawn from the pack of 52 cards.
Total Cards = 52. Numbered Cards = (2, 3, 4, 5, 6, 7, 8, 9, 10) 9 from each suit 4 × 9 = 36
P (E) = 36/52 = 9/13
400
Seats for Mathematics, Physics and Biology in a school are in the ratio 5 : 7 : 8. There is a proposal to increase these seats by 40%, 50% and 75% respectively. What will be the ratio of increased seats?
Originally, let the number of seats for Mathematics, Physics and Biology be 5x, 7x and 8x respectively.
Number of increased seats are (140% of 5x), (150% of 7x) and (175% of 8x).
140x 5x,150x 7xand175x 8x100100100
7x,21xand 14x.2
The required ratio = 7x :21x: 14x2
14x : 21x : 28x
2 : 3 : 4.
400
LM = 45mm
NM = 25mm
QR = 27mm
SR = ?
15mm
500
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.
P (G) × P (R) = (5/12) x (7/11) = 35/132
500
In a mixture 60 litres, the ratio of milk and water 2 : 1. If this ratio is to be 1 : 2, then the quantity of water to be further added is:
Quantity of milk =60 x2litres = 40 litres.3
Quantity of water in it = (60- 40) litres = 20 litres.
New ratio = 1 : 2
Let quantity of water to be added further be x litres.
Then, milk : water =40.20 + x
Now,40=120 + x2
20 + x = 80
x = 60.
Quantity of water to be added = 60 litres.
500
DA = 15yd
BA = 30yd
SR = 25yd
UR = ???
10 yd