M4maths Previous Puzzles

12 Jul 2022 Ratio & Proportion

A number of light bulbs were purchased to illuminate a house. However, only 3/5 of them were needed and 72 leftover light bulbs were returned. If only 70% of the cost of those returned, or Rs. 11088, was reimbursed, how much money was spent on illuminating the house?

OPtion

1) Rs. 23760
2) Rs. 16632
3) Rs. 31680
4) Rs. 21384
5) Rs. 33264
6) Rs. 14256
7) Rs. 22176
8) Rs. 28512
9) Rs. 27720
10) None of these

Solution

Bulbs used=3/5 .'. Bulbs returned=2/5
Let total bulbs=x, then (2/5)*x=72 ⇒ x=180
We know that Rs. 11088 represents 70% of the cost of 72 bulbs
.'. Full cost of 72 bulbs=(100/70)*11088=15840
Cost per bulb=15840/72=220
And cost which was not recovered=15840-11088=4752
Total cost = Cost(108 used bulbs) + Cost not recovered = 108*220 + 4752 = 28512 Rs.

Correct Option: 8 Best Solution (1)

G.S.Kantharao   2 years AGO

Left over =2/5=72
70%of 72=₹11088
Cost of 72=1108800*/(70)
=₹15840
Cost of 108=15840*3/2=₹23760
Total expenditure incurred=
₹23760+₹11088*3/7
=₹23760+₹4752=₹28512
My option is 8👈

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