time and work Model Questions & Answers, Practice Test for ibps rrb po officer scale 1 prelims 2024

Answer: (c)

The graph of speed vs time is plotted as shown. The area under the graph and the time axis gives the distance.

Required distance

= A(Δ OAP) + A(Δ BXA) + A(☐APQX)

= $1/2 × (1/2) × 40 + 1/2 × 10 × (3/2) + (3/2)$ × 40

= 10 + ${30}/4$ + 60 = 77.5 km.

Answer: (c)

Let the distance between the two stations be x km.

Then, $x/{50} - {10}/6 = x/{30} - {50}/6$

⇒ $x/{50} - 1/6 = x/{30} - 5/6$

or $x/{30} - x/{50} = 2/3$ or x = 50 km

Thus distance between the station A and B = 50 km

Alternate Method :

d = $({50 - 10}/{60})({50 × 30}/{50 - 30})$ = 50 km

Answer: (b)

Number of gaps between 21 telephone posts = 20.

Distance travelled in 1 minute = (50 × 20)m

= 1000 m = 1 km.

∴ Speed = $1/{1/60}$ km/h = 60 km/h

Answer: (a)

∴ One day's work of Ram = $1/6$

∴ One day's work of Shyam = $1/{12}$

One day's work together, Ram and Shyam

= $1/6 + 1/{12} = {2 + 1}/{12} = 3/{12} = 1/4$

∴ Two day's work together = $1/2$ (half of the work)

Answer: (d)

Required days = ${240 × 48}/{160}$

= 72 days