A person drives with constant speed and after some time he sees a milestone with 2 digits Then he travels

(b) 45. First time he sees 16. then 61(16+45). then 106(61+45). This satisfies the conditions given.
13 years agoHelpfull: Yes(16) No(6)

s=speed
"Then travels for 1 hour and sees the same 2 digits in reverse order."
10x + y + 1s(speed *time) = 10y + x
10x - x + s = 10y - y
9x + s = 9y

1 hours later he sees that the milestone has the same 2 digits with a 0 between them."
10y + x + s(again same) = 100x + y
10y - y + s = 100x - x
9y + s = 99x

Rearrange the above two equations for elimination
9x - 9y + s = 0
-99x+9y + s = 0
----------------adding eliminates y
-90x + 2s = 0
2s = 90x
s = 45x
x has to equal 1, then s = 45 mph (If x=2 and s=90 mph, when added to
a two digit milestone, could not be at another two digit milestone.)
13 years agoHelpfull: Yes(16) No(1)
let during the 1st hr men sees two digit number be(1hr):10x+y
now after an hr he sees reverse of the digit(2 hr) :10y+x
again he sees a 3-digit number which is same as previous but with 0 added so(3hr):100x+0+y
since,speed is constant then
distance covered in an hr=distance covered in 2 hr
(10y+x)-(10x+y)=(100x+y)-(10y+x)
-9x+9y=99x-9y
-108x+18y=0
18y=108x
9y=54x
so,x=1 y=6
ie:16 61 106
so to get the speed when we add 45 to 16 ie:45+16=61 similarly 61+45=106
so speed is 45mph
12 years agoHelpfull: Yes(13) No(1)
distance=speed*time
1 step-->2 digits 10x+y+(s*t)=10y+x---(1)
2 step-->same 10y+x+(s*t)=100x+0+y----(2)
solve this 2 equation
ANS=45
12 years agoHelpfull: Yes(2) No(0)
total matches =63

round matches No.of teams
6th 1 2
5th 2 4
4th 4 8
3rd 8 16
2nd 16 32
1st 32 64
--------------------------------------
Total matches:-63
13 years agoHelpfull: Yes(0) No(20)

Read Solution (Total 5)

TCS Other Question