RRB NTPC Prelims Model Paper 1 with solutions

Question : 35 of 100

Marks: +1, -0

Due to an increase of 30% in the price of pens, 6 pens less are available for Rs. 7.80. The present rate of pens per dozen is :

Solution:

(3) Original price per pen= Rs. x
New price per pen = Rs.

{13x}/10

∴{7. 8} /x-{7 8×10}/{13x}=6

⇒{7 .8 }/x –{7 .8× 10}/{13x}

⇒ 7.8[{13- 10}/{13x}]= 6

⇒7.8 × 3 = 13 × 6x

⇒ x ={7. 8× 3}/{13× 6} = Rs. 0.3

∴ New rate per dozen

= 12 ×{13× 0 .3}/10= Rs. 4.68

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