One student is asked to divide a half of a number by 6 and other half by 4 and then to add the two quantities.Instead of doing so the student divides the given number by 5.if the answer is 4 short of the correct answer then the number was
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Let the number be x,
Therefore, the two half would be x/2 and x/2
First half : divide by 6
x/2 ÷6 = x/12
Second half : divide by 4
x/2 ÷4 = x/8
Sum of two half = 3x/ 24 + 2x/24
= 5x/24
Operation done by student : x/5
Now,
5x/24 - 4 = x/5 (given condition)
5x - 96 = 24(x/5)
25x - 480 = 24x
(25 - 24)x = 480
Therefore the original number is 480
Therefore, the two half would be x/2 and x/2
First half : divide by 6
x/2 ÷6 = x/12
Second half : divide by 4
x/2 ÷4 = x/8
Sum of two half = 3x/ 24 + 2x/24
= 5x/24
Operation done by student : x/5
Now,
5x/24 - 4 = x/5 (given condition)
5x - 96 = 24(x/5)
25x - 480 = 24x
(25 - 24)x = 480
Therefore the original number is 480
rishabh3009:
hey brother ,can u explain in a much more simpler and tricky way.. pls .......
Well so take the number to be x, then divide by 2,since two halves. Then divide one by 4 and another by 6, then add them. Then separately divide the nunber(x) by 5. Then look at the conditions which states that it is 4 short if the answer so apply that. I am not sure how to simplify it any more
ohh thanks brother ,it helped a lot.....
hey , instead ive got a much more simpler trick by option test.. .
let the ans be assumed as 480,divide it equally being 240-240 .now half of a number is divided by 6 and other by 4 ,we get 40 & 60 .Now the student divides the given number by 5 ,hence he gets values as 8 & 12,hence being 4 short ,the correct number was 480 ,hope it helps ....
yeah you could do that but in mathematics you usually assume any unknown value to be x because sometime the numbers guvej might have complex multiples and getting a number for that might be difficult. but yeah it works
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