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The number of prime numbers which are less then 100 is? |
A) 24 B) 25 C) 26 D) 27 Correct Answer : 25 Explanation : Prime num bers less than 100 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97. Thus, there are 25 prime numbers less than 100 |
In an arithmetic progression, if 17 is the 3rd term, - 25 is the 17th term, then -1 is which term? |
A) 10 B) 11 C) 9 D) 12 Correct Answer : 9 Explanation : a3 = a + 2d = 17 …(i) - 14d = 42 Let, nth term of the given AP is - 1 then |
Twice the first of three consecutive even integer is 6 more than the second integer. What is the third integers? |
A) 6 B) 8 C) 10 D) 12 Correct Answer : 12 Explanation : Let the three consecutive even integers are X, X+2, X+4 Hence, third integer = X + 4 = 8 + 4 = 12 |
If a, b and c are digits, then abc + bca + cab is divisible by? |
A) 22 B) 37 C) 99 D) 101 Correct Answer : 37 Explanation : If a ,b ,c are digits then the numbers formed can be: The sum is abc + bca + cab= (100a + 10b + c)+(100b + 10c + a)+(100c + 10a + b) |
The common difference of the AP √12,√27,√48,√75 is ? |
A) √2 B) 3 C) √3 D) √12 Correct Answer : √3 Explanation : The given AP is √12,√27,√48,√75 |
There are 22 terms in an arithmetic sequence. The sum of the first and last terms is 94. If the 11th term is 45, then the 12th term is ? |
A) 48 B) 49 C) 50 D) 51 Correct Answer : 49 Explanation : tn = a + (n – 1)d where tn = nth term, a= the first term , d= common difference 11th term, a + 10 d = 45 from eq1 - eq2, Hence 12th term is, (a + 11 d)= 5 + 11*4 = 49 |
The difference between the place value of 4 and 2 in the number 833749502 is ? |
A) 39098
B) 39998
C) 49998
D) 30098
Correct Answer : 39998 Explanation : Place value of digit 4 in the number = 40000 Their difference = 40000 - 2 = 39998 |
The number of natural numbers less than 100 which have exactly 3 factors is ? |
A) 10
B) 4
C) 12
D) 33
Correct Answer : 4 Explanation : Numbers less than 100 that have exactly three factors are 4, 9, 25 and 49. All of these numbers are squares of prime numbers, which means that their only factors are one, themselves and their square roots.
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Find the sum of the first 20 terms of the series : 8, -3, 11, -6, 14, -12, 17, -24,....... ? |
A) -2854
B) 2854
C) -3069
D) 3069
Correct Answer : -2854 Explanation : 8, -3, 11, -6, 14, -12, 17, -24,....... odd term: next value is +3 of previous one even term: next value is double of previous one total => 215 + (-3069) = -2854 |
Find the total number of terms in the series : -3, 1, 5, 9,............., 101 ? |
A) 25
B) 26
C) 27
D) 28
Correct Answer : 27 Explanation : the common diffrence is d= 4 and first term a = -3 nth term of AP, tn = a+(n-1)d |
How many numbers between 1200 to 1500 are multiple of 13? |
A) 21
B) 22
C) 23
D) 24
Correct Answer : 23 Explanation : The first term divisible by 13 after 1200 is 1209, the last term before 1500 divisble by 13 is 1495 Let n be the number of terms multiple by 13 between 1200 and 1500 |
How many 2 digit numbers are divisible by 6? |
A) 12
B) 13
C) 14
D) 15
Correct Answer : 15 Explanation : The first two digit number divisible by 6 is 12, and last two digit divisible by 6 is 96 Tn=a1+(n-1)d Let a=12 , d=6, Tn=96 |
The geometric mean of three observations 40, 50 and X is 10, then the value of X is ? |
A) 1/2
B) 1
C) 2
D) 3
Correct Answer : 1/2 Explanation : Geometric mean observations=40,50,x |
The value of product 6 1/2 * 6 1/4 * 6 1/8 * 6 1/16 * -----∞ upto infinite terms? |
A) 1
B) 6
C) 36
D) 216
Correct Answer : 6 Explanation : 6 1/2 * 6 1/4 * 6 1/8 * 6 1/16 * -----∞ => 6 (1/2 + 1/4 + 1/8 + 1/16 -----∞) 1/2 + 1/4 + 1/8 + 1/16 -----∞ is geometric series [a = 1/2, r = 1/2] Hence , 6 (1/2 + 1/4 + 1/8 + 1/16 -----∞) => 6 (1) => 6 |
A person is to count 4500 currency notes. Let an denote the number of notes he counts in the nth minute. If a1 = a2 = .... = a10 = 150 and a10 , a11 ,... are in an AP with common difference – 2, then the time taken by him to count all notes is ? |
A) 24 minutes
B) 34 minutes
C) 125 minutes
D) 135 minutes
Correct Answer : 34 minutes Explanation : Suppose he takes n minutes to count 4500 notes. a10 , a11 ,... are in an AP with common difference −2 then a10=150 and a11=148 |
Find the sum of the given series: 3 + 9 + 27 + 81 + 243 + 729 + 2187 + 6561 |
A) 9840
B) 9855
C) 7960
D) 8892
Correct Answer : 9840 Explanation : 3 + 9 + 27 + 81 + 243 + 729 + 2187 + 6561 a{(rn - 1)/(r - 1)}, a is first term, r is common ratio, n is number of terms 3 * {(38 - 1)/(3 - 1)} The sum of the series is 9840 |