Model 2 Vehicles in x/y of its usual speed Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (d)

Time and speed are inversely proportional.

$4/3$ of usual time –usual time = $3/2$

$1/3$ usual time = $3/2$

Usual time = ${3 × 3}/2$

$9/2 = 4{1}/2$ hours

Using Rule 8,

Here, A = 3, B = 4, t= $3/2$

Usual time = $\text"A"/\text"Diff of A and B"$ × time

= $3/{(4 - 3)} × 3/2 = 4{1}/2$ hrs.

Answer: (c)

1 m/sec = $18/5$ kmph

20 m/sec = ${20 × 18}/5$

= 72 kmph

Answer: (c)

1 hr 40 min 48 sec

= 1 hr $(40 + 48/60)$ min

= 1 hr $(40 + 4/5)$ min

= 1 hr $204/5$ min

= $(1 + 204/300)$ hr = $504/300$ hr

Speed = $42/{504/300}$ = 25 kmph

Now, $5/7$ usual speed = 25

Usual speed = ${25 × 7}/5$ = 35 kmph

Answer: (b)

Speed of car = x kmph.

Distance = Speed × Time = 25x km.

Case II,

Speed of car = ${4x}/5$ kmph.

Distance covered

= ${4x}/5 × 25$ = 20x km.

According to the question,

25x - 20x = 200

5x = 200

x = $200/5$ = 40 kmph.