On this Diwali, Akash a tech guy, decorated his home by a series of LED lights of three different colours: blue, red and green where he uses total 100 LED lights and also spends exactly Rs. 100 on making this series. If cost of blue LEDs is Rs. 4 for 3, red LEDs Rs. 3 for 9 and green LEDs Rs. 7 for 10, then which of the following can be the number of blue LEDs in the series ?
B + R + G = 100 --- (i) and
B*(4/3) + R*(3/9) + G*(7/10) = 100 ⇒ 40B + 10R + 21G = 3000 ---(ii)
Multiplying eqn. (i) by 10 and subtracting it from (ii), we get 30B + 11G = 2000
B = (2000 - 11G)/30
We get the integer value of B for G=10 and 40, so that count of total lights is 100.
Therefore combinations of Blue, Red & Green are B=63, R=27, G=10 OR B=52, R=8, G=40
Correct Option 5)