Math Puzzle 20

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This math puzzle 20 is on exponents,radical,logarithm,logical reasoning etc.

1) The average age of 6 boys in a group is 17 years. If Andy who is 26 years old is replaced by David, the average age of the group becomes 16 years. How old is David?
A. 2 years     B. 4 years     C. 6 years    D. 8 years     E. 20 years

2) The average height of a set of students is x. A new student of height x + 10 joins the group. Then, which of the following statements is true
I The new average height of the students will be more than x.
II The new average height of the students will be less than x.
III Nothing can be predicted about the new average as x is not known.
A. I only     B. II only     C. III only    D. I and II only     E. None of these

3) The following recipe is used for making 500g chocolate cake.

Ingredients	Mass
Egg	150 g
Milk	75 g
Butter	30 g
Chocolate	125 g
Flour	120 g

If Jane wants to make 2 kg of chocolate cake then how much chocolate will she require?
A. 250 g     B. 500 g     C. 750 g     D. 1000 g
E. None of these

4)

-	6 am - 2pm	2 pm - 10 pm	10 pm - 6 am	General shift
Number of workers	200	230	120	350

In a factory, number of workers in different shifts is given in the table. What percentage of workers work in the General Shift?
A. 400/18     B. 700/18     C. 12     D. 23     E. 35

5)

-	6 am - 2pm	2 pm - 10 pm	10 pm - 6 am	General shift
Number of workers	200	230	120	350

In a factory, number of workers in different shifts is given in the table. What more percentage of workers work in General Shift compared to number of workers from 2.00pm to 6.00am?
A. 0     B. 1200/35     C. 2300/35     D. 120     E. 230

6) If ab is negative, which of the following must be true?
I a > 0 > b
II a > b > 0
III 0 > a > b
A. I only     B. II only    C. III only     D. I and III only    
E. I and II only

7) If x - y + z = 8 then 4x - 4y + 4z - 2 =?
A. 27     B. 28    C. 29    D. 30     E. 34

8) If a + 1/a = 3, then a² + 1 / a² ?
A. 5     B. 7     C. 9     D. 10     E. 11

9) If log p = a and log q = b, log√p / √q =?
A. (a - b)/2    B. 2 (a - b)    C. (a + b)/ 2     D. 2 (a + b)     E.√(a - b)

10) If f (x) =x² + 1 and g (x) = 3x - 2, then f [g (x)] = ?
A. 3x² + 1     B. x² - 5     C.9x² - 12x + 3     D. 9x² - 12x + 2     E. 9x² - 12x

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Math puzzle 20

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