Let the distance travelled on foot be x km.
Then, distance travelled on bicycle = (61 -x) km.
So,
x
+
(61 -x)
= 9
4
9
9x + 4(61 -x) = 9 x 36
5x = 80
x = 16 km.
So,
x
+
(61 -x)
= 9
4
9
9x + 4(61 -x) = 9 x 36
5x = 80
x = 16 km.
Then,
x
–
x
=
40
2y(y + 3) = 9x ….(i)
y
y + 3
60
And,
x
–
x
=
40
y(y – 2) = 3x ….(ii)
y -2
y
60
On dividing (i) by (ii), we get: x = 40.
600
m/sec.
5 x 60
= 2 m/sec.
Converting m/sec to km/hr (see important formulas section)
=
2 x
18
km/hr
5
= 7.2 km/hr.
5
75
75
Let the actual speed be x km/hr.
Then,
5
x x
126
= 42
7
75
x =
42 x 7 x 75
= 35 km/hr.
5 x 126
Then,
x
=
x + 20
10
14
14x = 10x + 200
4x = 200
x = 50 km.
Time taken to cover 9 km =
9
x 60
min
= 10 min.
54
Then, speed of the train =
150
x
=
3
x
kmph.
100
2
75
–
75
=
125
x
(3/2)x
10 x 60
75
–
50
=
5
x
x
24
x =
25 x24
= 120 kmph.
5
Then, 8x =
400
= 100
4
x =
100
= 12.5
8
Speed of first train = (7 x 12.5) km/hr = 87.5 km/hr.
21
24
x
+
x
= 20
21
24
15x = 168 x 20
x =
168 x 20
= 224 km.
15
Then,
x
–
x
= 2
10
15
3x – 2x = 60
x = 60 km.
Time taken to travel 60 km at 10 km/hr =
60
hrs
= 6 hrs.
10
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
Required speed =
60
kmph.
= 12 kmph.
5