Question

If 10 masons working 7 hours dailycan build 28 water tank in 16 days,then how many days will 12 masons working 6h daily take to build 36 water tanks?

Answer 1

Answer:

we need 20 days

Step-by-step explanation:

Since we are given following data (in tabular form)

mason      hours     water tanks        days

 10               7                28                   16

  12              6                36                    x

Since

Days are directly proportional to number of water tanks and inversely proportional to both number of hours and masons that is

days ∝ water tanks

days ∝ 1 / hours

days ∝ 1 / masons

So

By combining all the proportionalities we get  

     x / 16 = (36 /28)×(7/6)×(10/12)

⇒        x = 16×(36 /28)×(7/6)×(10/12)

⇒         x = 20

So we need 20 days

             

Answer 2

12 masons working 6 hours daily can build 36 water tank in 20 days

Step-by-step explanation:

Given as :

If 10 masons working 7 hours daily can build 28 water tank in 16 days

i.e number of men = $M_1$ = 10

    number of days = $D_1$ = 16

    number of hours = $T_1$ = 7

    number of tank build = $W_1$ = 28

Let 12 masons working 6 hours daily can build 36 water tank in x days

i.e number of men = $M_2$ = 12

    number of days = $D_2$ = x

    number of hours = $T_2$ = 6

    number of tank build = $W_2$ = 36

According to question

$\dfrac{men\times days\times hours}{work}$  = constant

So, $\dfrac{M_1\times D_1\times T_1}{W_1}$   =  $\dfrac{M_2\times D_2\times T_2}{W_2}$

Or,  $\dfrac{10\times 16\times 7}{28}$ = $\dfrac{12\times x\times 6}{36}$

Solving each side , we get

     40 = 2 x

∴    x = $\dfrac{40}{2}$

i.e x = 20 days

So, 12 masons working 6 hours daily can build 36 water tank in x = 20 days

Hence, 12 masons working 6 hours daily can build 36 water tank in 20 days Answer