Q. In a game, the probability of winning is 0.25. If a player plays 4 times, what is the probability of winning at least once?
A.0.75
B.0.84
C.0.93
D.0.99
Solution
The probability of losing all 4 games is (0.75)^4 = 0.3164. Therefore, the probability of winning at least once is 1 - 0.3164 = 0.6836, approximately 0.84.
Q. In a geometric series where the first term is 4 and the common ratio is 2, what is the sum of the first 5 terms? (2023)
A.60
B.62
C.64
D.68
Solution
The sum of the first n terms of a geometric series is a(1 - r^n) / (1 - r). Here, a = 4, r = 2, n = 5. So, 4(1 - 2^5) / (1 - 2) = 4(1 - 32) / -1 = 124.
Q. In a harmonic progression, if the first term is 2 and the second term is 3, what is the third term?
A.4
B.5
C.6
D.7
Solution
In a harmonic progression, the reciprocals of the terms form an arithmetic progression. The reciprocals of 2 and 3 are 1/2 and 1/3. The common difference is 1/3 - 1/2 = -1/6. The third term's reciprocal will be 1/3 - 1/6 = 1/6, so the third term is 6.
Q. In a harmonic progression, if the first term is 2 and the second term is 4/3, what is the third term?
A.1
B.3/2
C.2/3
D.1/2
Solution
In a harmonic progression, the reciprocals of the terms form an arithmetic progression. The reciprocals of the first two terms are 1/2 and 3/4. The common difference is 1/4, so the reciprocal of the third term is 1/2 + 1/4 = 3/4. Therefore, the third term is 1/(3/4) = 4/3.
Q. In a harmonic progression, if the first term is 4 and the second term is 2, what is the common difference of the corresponding arithmetic progression?
A.1
B.2
C.3
D.4
Solution
The reciprocals of the terms are 1/4 and 1/2. The common difference is 1/2 - 1/4 = 1/4.
Q. In a harmonic progression, if the first term is 4 and the second term is 8, what is the third term?
A.12
B.16
C.20
D.24
Solution
The reciprocals are 1/4 and 1/8. The common difference is 1/8 - 1/4 = -1/8. The third term's reciprocal will be 1/8 - 1/8 = 0, hence the third term is 16.
Q. In a harmonic progression, if the first term is 4 and the second term is 8, what is the common difference of the corresponding arithmetic progression?
A.1
B.2
C.3
D.4
Solution
The reciprocals are 1/4 and 1/8. The common difference is 1/8 - 1/4 = -1/8, which means the common difference of the corresponding arithmetic progression is 1/8.
Q. In a harmonic progression, if the first term is a and the second term is b, what is the formula for the nth term?
A.1/(1/n + 1/a)
B.1/(1/n + 1/b)
C.1/(1/a + 1/b)
D.1/(1/a - 1/b)
Solution
The nth term of a harmonic progression can be expressed as 1/(1/a + (n-1)d) where d is the common difference of the corresponding arithmetic progression.
Q. In a mixture of two liquids, if the first liquid is 25% alcohol and the second is 75% alcohol, what is the overall percentage of alcohol if equal volumes of both liquids are mixed?
Q. In a mixture of two liquids, if the first liquid is 60% pure and the second is 80% pure, what is the overall purity if they are mixed in equal volumes?
Q. In a mixture of two types of tea, if the first type costs $5 per kg and the second type costs $7 per kg, what is the cost per kg of the mixture if they are mixed in the ratio 2:3?