time and work Model Questions & Answers, Practice Test for ssc chsl tier 1 2023

Answer: (b)

If both the pumps are opened together, then the tank will be emptied because the working efficiency of pump empting is more than that of the pump filling it. Thus in 1 min net proportion of the volume of tank filled

= $(1/8 - 1/{16}) = 1/{16}$

or the tank will be emptied in 16 min

⇒ $1/2$ tank will be emptied in 8 min.

Answer: (a)

Let the duration of the flight be x hours. Then,

${600}/x - {600}/{x + 1/2} = 200⇒{600}/x - {1200}/{2x + 1}$ = 200

⇒ x(2x + 1) = 3⇒$2x^2$ + x - 3 = 0⇒(2x + 3) (x – 1) = 0

⇒x = 1 hr. [neglecting the –ve value of x].

Answer: (d)

10 mason 8 hrs 50 m wall 25 days

1 mason 8 hrs 50 m wall 25 × 10 days

1 mason 1 hr 50 m wall 25 × 10 × 8 days

1 mason 1 hr 1 m wall ${25×10×8}/{50}$ days

1 mason 1 hr 36 m wall ${25×10×8×36}/{50}$ days

1 mason 6 hr 36 m wall ${25×10×8×36}/{50×6}$ days

15 mason 6 hr 36 m wall ${25×10×8×36}/{50×6×15}$ days

= 16 days

Answer: (e)

∵15 men can do the work in 3 days.

∴1 man can do the work in 3 × 15 days.

∴ 10 men can do the same work in

${3×15}/10=9/2=4{1}/2$ days

Answer: (b)

Let the original speed = x

Total time taken = 3 hr

⇒3 = ${63}/x + {72}/{x + 6}$

⇒(x) (x + 6) = 21(x + 6) + 24(x)

⇒$x^2$ – 39x – 126 = 0

⇒$x^2$ – 42x + 3x = 126 = 0

⇒(x – 42) (x + 3) = 0

x = 42, x = – 3

x = – 3 is rejected.

Hence original speed was 42 km/hr.