Model 1 Basic Time & Distance using formula Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (c)

Using Rule 1,

Remaining time

= $2/5 × 15 = 6$ hours

Required speed

= $60/6$ = 10 kmph

Answer: (b)

Using Rule 1,

Man's speed = $\text"Distance"/ \text"Time"$

= $a/b$ kmph = ${1000a}/b$ m/hour

Time taken in walking 200 metre

= $200/{{1000a}/b} =b/{5a}$ hours

Answer: (b)

Using Rule 1,

Speed = $\text"Distance"/\text"Time" = 250/75$

= $10/3$ m/sec = $10/3 × 18/5$ km/hr

[Since, 1 m/s = $18/5$ km/hr]

= 2 × 6 km/hr. = 12 km/hr.

Answer: (c)

Let the distance be x km.

Total time = 5 hours 48 minutes

= $5 + 48/60 = (5 + 4/5)$ hours

= $29/5$ hours

$x/25 + x/4 = 29/5$

${4x + 25x}/100 = 29/5$

5 × 29x = 29 × 100

$x = {29 × 100}/{5 × 29}$ = 20 km.

Here, x = 25, y = 4

Average speed = ${2xy}/{x + y}$

= ${2 × 25 × 4}/{25 + 4} = 200/29$

Total Distance = $200/29 × 5{4}/5$

= $200/29 × 29/5$ = 40 km

Required distance = 20 km

Answer: (b)

90 km = 12 × 7km + 6 km.

To cover 7 km total time taken = $7/18$ hours + 6 min. = $88/3$ min.

So, (12 × 7 km) would be covered in $(12 × 88/3)$ min.

and remaining 6km is $6/18$ hrs or 20 min.

Total time = $1056/3$ + 20

= $1116/{3 × 60}$ hours = 6$1/5$ hours

= 6 hours 12 minutes.

Answer: (b)

Let the distance between A and B be x km, then

$x/9 - x/10 = 36/60 = 3/5$

$x/90 = 3/5$

$x = 3/5 × 90$ = 54 km.

Using Rule 9,

Here, $S_1 = 9, t_1 = x, S_2 = 10, t_2 = x - 36/60$

$S_1t_ 1 = S_2t_ 2$

$9 × x = 10(x - 36/60)$

9x = 10x - 6 = 6

Distance travelled = 9 × 6 = 54 km