(1) If  19  dolls cost  Rs.  247,  what do 29 dolls cost  ?

Soln.      19    dolls  cost   Rs.    247

29      ”       ”         ”     ( ? )

   =   Rs.  377

(2) A rope makes 180 rounds of  a  cylinder with base radius  18  cm.  How many times can it go round a cylinder with base  radius  27  cm.  ?

Soln.      With  radius  18  cm., the  no. of rounds of  a  cylinder is  180

”             ”   27           ”             ”          ”            ”             ( ? )

 =     120   Rounds

(3) If   35  men can do a piece of  work in 42 days, in how many days will 15 men do it  ?

Soln. M₁  =  35  men,  D₁  =  42  days,   M₂  =  15  men,   D₂  =  ( ? )  days

M₁ D₁  =  M₂ D₂

∴  35  ×  42  =   15  ×  D₂

∴   =   D₂       ∴   D₂    =    98    days

(4) If  25 men can build a wall 120 m long in 8 days, what length of  similar wall can be  built by 35 men in  3 days ?

Soln. M₁ = 25 men,  D₁ = 8 days,  W₁ = 120 m,   M₂ = 35 men,  D₂ = 3 days,  W₂ = ( ? ) m

= 

∴

∴  W₂  = 

∴  W₂  =  63  m

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