M4maths Previous Puzzles

26 Aug 2022 Ratio & Proportion

If a:b=9:7, b:c=5:8 and 5a –3b + 4c = 344, then the value of c is

OPtion

1) 45
2) 35
3) 65
4) 28
5) 56
6) 70
7) 54
8) 42
9) 63
10) None of these

Solution

5a - 3b + 4c = 344
As we require value of c, therefore expressing a and b in terms of c in above equation.
Given, a/b=9/7, b/c=5/8 ⇒ a : b : c = (9x5) : (7x5) : (8x7) = 45 : 35 : 56
.'. a/c=45/56 ⇒ a=45c/56 and b=5c/8
5a –3b + 4c = 5x(45c/56) - 3x(5c/8) + 4c = 344
Solving, we get c=56
Correct Option 5)

Correct Option: 5 Best Solution (2)

Dr.Dipin Singh   2 years AGO

As per given statement,
a:b:c =45:35:56
Hence
5*45x -3*35x +4*56x=344
x=1
Hence c=56

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RAMADURAI NATESAN   2 years AGO

Given :7a = 9b 0r 56a = 72b. 8b = 5c or 72b = 45c.
a = 45c/56 and b = 45c/72c = 5c/8.
Substituting a and b in terms of c in given equation,
c( 225/56 + 4 - 15/8 ) = 344. Solving c = 56.

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