Question

In an examination, there are five subjects and each has the same maximum. A boys marks are in the ratio 3 : 4 : 5 : 6 : 7 and his aggregate is 3/5th of the full marks. In how many subjects did he get more than 50% marks?

Answer 1

Answer:

He scored more than 50% in 3 subjects

Answer 2

Answer:

The answer is 3 subjects

Step-by-step explanation:

given data

number of subjects in an examination = 5

each subject has same maximum marks

the ratio of the marks that the boy got = 3: 4: 5: 6: 7

his aggregate is 3/5th of full marks  

here we need to find number of subjects in which he got more than 50%

Let x be the maximum marks of 5 subjects

the total maximum marks in 5 subjects = 5x

50% of x marks = $\frac{50}{100} (x)$ = 0.5x

here the boy's aggregate of gained marks = $\frac{3}{5} th$ of 5x

                                                                       = $\frac{3}{5} (5x)$ = 3x

let 3a, 4a, 5a, 6a and 7a be the marks in 5 subjects

   3a + 4a + 5a + 6a + 7a = 3x

                                 25a = 3x

                                      a = $\frac{3x}{25}$    

marks in each subject

3a = $\frac{3(3x)}{25}$ = $\frac{9x}{25}$ = 0.36x  

4a =   $4(\frac{3x}{25})$ = $\frac{12x}{25}$   = 0.48x

5a = $(5) \frac{3x}{25}$ = $\frac{3x}{5}$   = 0.6x

6a = $6(\frac{3x}{25})$ = $\frac{18x}{25}$ = 0.72x

7a = $7(\frac{3x}{25} )$ = $\frac{21x}{25}$  = 0.84x

the marks of boy in which he got more than 50% of x are 0.6x, 0.72x and 0.84x  

the boy got more than 50% marks in 3 subjects