If 15 workers can build a wall in 48 hrs, how many workers will be required to do the same work in 30 hrs?

Correct option is (A) 27 Given that 36 men can built a wall in 12 days. \(\therefore\) Total work = 36 \(\times\) 12 Let 16 men can built the wall in x days. \(\therefore\) Total work = 16 \(\times\) x \(\because\) Both work...

Correct option is (D) \(\frac{(a+1)^2}{a+2}\) Work done by (a+1) works in (a+1) days = (a+1) (a+1) \(=(a+1)^2\) Number of days required to complete the same work by (a+2) members \(=\frac{\text{Total work}}{a+2}\) \(=\frac{(a+1)^2}{a+2}\)

Correct option is (A) 24 Number of required workers \(=\frac{15\times48}{30}\) \(=\frac{48}2\) = 24

Correct option is (A) \(112\frac12\,km/hrs\) Distance covered by train in \(2\frac12\) hrs = speed \(\times\) time = 90 \(\times\) \(2\frac12\) km = 90 \(\times\) \(\frac52\) km = 45 \(\times\) 5 km = 225 km \(\therefore\) Speed required to covered same distance (225 km) in 2 hours \(=\frac{Distance}{Time}\) \(=\frac{225}2\,km/hrs\) \(=112\frac{1}2\,km/hrs\)

Correct option is (B) 13 1/2 Work done to complete the wall = Work done by 30 labourers in 9 days = Work done by 20 labourers in x days \(\therefore 20\times x=30\times9\) \(\Rightarrow x=\frac{30\times9}{20}=\frac{27}2\,days\) \(=13\frac12\,days\)

Correct Answer - 16