percentage problems
1. In an election between two candidates, one got 55 % pf the total valid votes , 20 % of the votes were invalid. if the total number of votes was 7500, the number of valid votes that the other candidate got was??
find total votes = 20 % percent invalid so => 80/100*7500 = 6000
one got 55 % vote. we need to find another candidate vote
so => 45/100 * 6000 = 2700 votes
2. A fruit seller has some apples.he sells 40 % apples ans still has 420 apples .Originally, he had
initially he had 100 % apple, he sold 40 % apple
we need to find for 60 percent apple so => 60/100 *x = 420
x = 420 * 100/60 = 700
initally he had 700 apples
3.A bag contains 50p, 25p and 10 p coins in the ratio 5:9:4 amounting to Rs 206 .Find the number of coins of each type
Explanation
Let the number of 50 p, 25p and 10 p coins be 5x, 9x, and 4x respectively
then 5x/2 + 9x/4+ 4x/10 = 206
50x + 45x + 8x =4120
103x = 4120
x = 20
Number of 50 p coins = 5*40 = 200
Number of 25p coins = 9* 40 = 360
Number of 10 p coins = 4 * 40 = 160
4. Two pipes can fill a tank in 10 hours and 12 hours respectivley while a third pipe empties the full tank in 20 hours . If all the three pipes operates simultaneously, in how much time will the tank be filled ?
Net part filed in 1 hour = (1/10 + 1/12-1/20)
= 8/60 = 2/25
The tank will be full in 15/2 hrs = 7 hrs 30 mins
5. A and B together can complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how many days can B alone complete that work?
A +B )’S 1 day work = 1/4 , A’s 1 day work = 1/12
B’s 1 day work = (1/4–1/12) = 1/6
Hence B alone can complete the work in 6 days
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