Question

Write 'T' for true and 'F' for false

(i) If 10 pipes of the same diameter can fill a tank in 24 minutes, then 8 pipes would fill it in 19 min 20 sec.
(ii) If 8 men can finish a piece of work in 40 days, then 10 men can finish it in 32 days.
(iii) A tree 6 m tall casts a shadow of length 4 m. At the same time a flag casts a shadow of length 50 m. The lenght of the pole is 75 m.
(iv) If a worker takes $\frac{2}{3}$ hour to make a toy, then he will make 12 toys in 8 hours.

Answer 1

(i) F
10 pipes fill the tank in 24 min.
1 pipe will fill the tank in 24 $\times$10 min. (Less pipes, more time taken)
8 pipes will fill the tank in $\frac{24\times 10}{8}$ = 30 min (More pipes, less time taken)

(ii) T
8 men finish the work in 40 days.
1 man finishes the work in 8$\times$40 days. (Less men, more days taken)
10 men will finish the work in $\frac{8\times 40}{10}$ = 32 days (More men, less days taken)

(iii) T
A 6 m tall tree casts a shadow of length 4 m.
A 1 m tall tree cast a shadow of length $\frac{4}{6}$ m.
A 75 m tall pole will cast a shadow of length $\frac{4}{6}\times 75$ =50 m

(iv) T
1 toy is made in $\frac{2}{3}$ h. (Less toys, less time taken)
12 toys can be made in $\frac{2}{3}\times 12$ = 8 h (More toys, more time taken)