Math Puzzles Questions

This can be done in two ways

1. A to G : 2, 3, 7, 6, 5, 1, 4 

2. A to G : 4, 3, 7, 5, 6, 2, 1

From the hints,

Only two options for 1st and 2nd digits => 4,2 and 9,3 since it is single digits

Sum of second and third digit  = 10 

If 2 => 3rd digit = 8

If 3 => 3rd digit = 7

4th digit = 2nd digit + 1 => (2+1 =3) or (3+1 = 4)

Sum of all digits = 30

Let 5th digit be x

=> 1st possibility = 4 + 2 + 8 + 3 + x = 30 => x = 13 (Not possible since it has 2 digits)

=> 2nd possibility = 9 + 3 + 7 + 4 + x = 30 => x = 7

Therefore, the PIN is 93747 

Given two trains of length = 180 mts + 180 mts 

The distance is = Length of trains = 360 mts 

Speed = 58 - 50 = 8 kmph x 5/18 m/s

Then, Time = dis/speed = (360x18) / (8x5) = 162 sec.

The logic in the challenge is

 81x6 = 9x6 = 54

144x7=84

Similarly, 64x8 = 8x8 = 64.

The puzzle's logic is

1st figure : (9-7) + (8-5) = 2 + 3 = 5

2nd figure : (15-6) + (11-2) = 9 + 9 = 18

similarly, 3rd figure : (9-6) + (17-5) = 3 + 12 = 15.

Let the integer be x. Then,

 x2-20x = 156

(x + 6)(x - 26) = 0

x = 26

The integer is 26.

To get a pair of black rings 100 percent certain

27 blue + 17 red + 2 black = 40 rings should be taken out

Then only we can get 100 % a pair of black rings. 

Let the required number be 'N'

given that its quarter i.e; N/4 exceeds its double i.e, 2N by 7

=> N/4 + 7 = 2N

=> N + 28 = 8N

7N = 28

N = 4.