1. The unit digit in the product (624 * 708 * 913 * 463) is: 4 men and 5 boys can do a piece of work in 20 days while 5 men and 4 boys can do the same work in 16 days. In how many days can 4 men and 3 boys do the same work?
Answer: Option D
Explanation:
Unit digit in the given product = Unit Digit in (4*8*3*3) = 8
2. In an entrance exam, 3 marks is awarded for every correct answer and (-1) for every wrong answer. If a student gets 38 marks after attempting all questions, find the number of questions answered correctly if the total questions were 70.
Answer: Option C
Explanation:
Let x be the number of questions answered correctly. Hence, number of questions whose answer were wrong = (70 – x)
3*x + (70 – x)*(-1) = 38
4x = 38 + 70 = 108
x = 27
3. If in a book a total of 3209 digits are used for numbering, then find out the total number of pages in the book.
A. 1079
B. 1000
C. 1100
D. 1075
Answer: Option A
Explanation:
Number of digits used in 1 digit numbers = 1*9 = 9
Number of digits used in 2 digit numbers = 2*90 = 180
Number of digits used in 3 digit numbers = 3*900 = 2700
Number of digits used in 1 digit numbers = 3209 – (9+180+2700) = 320
Hence, number of pages with 4 digit number = [latex]\frac{ 320}{4}[/latex] = 80
Total number of pages = 1079
4. How many numbers between 100 and 600 are divisible by 2, 3, and 7 together?
A. 11
B. 12
C. 14
D. cannot be determined
Answer: Option B
Explanation:
As the division is by 2, 3, 7 together, the numbers are to be divisible by: 2*3*7 = 42
The limits are 100 and 600
The first number divisible is 42*3 = 126
To find out the last number divisible by 42 within 600:
600/42 = 14.28
Hence, 42*14 = 588 is the last number divisible by 42 within 600
Hence, total numbers divisible by 2, 3, 7 together are (14 – 2) = 12
5. What will come in place of the question mark (?) in the following question?
112.36 + 225.05 + ? = 815.30
474.46
B. 474.46
C. 524.41
D. 564.40
Answer: Option B
Explanation:
815.30 - ( 112.36 + 225.05) = ?
= 477.89