#DILR-23

Ravi's grandfather, as a part of his will, bequeathed to Ravi a safe, which had exactly four combination locks- L1, L2, L3 and L4. In order to open the safe, Ravi must enter exactly four keys K1, K2, K3 and K4, in each of L1, L2, L3 and L4 respectively. While K1 can be entered first, K2 can be entered only after L1 is unlocked; K3 can be entered only after L2 is unlocked and so on. Each key is a four-digit number (with the first digit at the extreme left and the last digit at the extreme right). while Ravi was not aware of the keys of any locks, also given to him along with the box, was parchment containing the following clues;
1)The first digit of K1 is the same as the last digit of K3.
2)K2 and K4 have the same sets of digits but not necessarily in the same order.
3)The number represented by the last two digits of K3 and the number represented by the first two digits of K2 are both squares of odd numbers other than 1.
4)The number represented by the last two digits of K4 appears exactly three times across all four keys.
5)The number represented by the first two digits of K1 is a perfect square and exactly twice the number represented by the second and third digit of K4.
6)The number represented by the last two digits of K1 is even and the last digit of K4 is 5.
7)The digit 5 appears at least once in each of four keys. 

1)What is the number of times 1 appear across all the four keys?
(a)1
(b)2
(c)3
(d) (b) or (c)

2)What is the value of L3?

3)If each time that Ravi enters a key(correct or incorrect) it is called a trial. What is the maximum number of trials that can be used to open the safe?
(a)4
(b)8
(c)10
(d)13

4)Which can be the value of K1?
(a)2548
(b)6454
(c)1652
(d)3658

Solution-