A farmer built a fence around his square plot. He used 27 fence poles on each side of the square. How many poles did he need altogether ?

Since each pole at the corner of the plot is common to its two sides, so we have :

Total number of poles needed = 27 x 4 - 4 = 108 - 4 = 104.

In a city, 40% of the adults are illiterate while 85% of the children are literate. If the ratio of the adults to that of the children is 2 : 3, then what percent of the population is literate ?

Ans :

Today is Varun's birthday. One year, from today he will be twice as old as he was 12 years ago. How old is Varun today ?

Let Varan's age today = x years.

Then, Varan's age after 1 year = (x + 1) years.

Therefore x + 1 = 2 (x - 12)  x + 1 = 2x - 24  x = 25.