model 7 marks scored in examinations Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (b)

Successful boys in English or Maths or both

= 80 + 85 – 75 = 90%

Unsuccessful boys = 10%

Total number of boys = $100/10 × 45$ = 450

Answer: (d)

Let marks obtained by Supriyo = x

${9x}/10 = 81 ⇒ x = {81 × 10}/9 = 90$

Answer: (a)

Let total number of students = 100

Number of failures in Maths = 34

Number of failures in English = 42

Number of failures in both subjects = 20

Number of failures in Maths or English or both

= 34 + 42 – 20 = 56

Number of students who passed in both subjects

= 100 – 56 = 44

The required percentage = 44%

Using Rule 23,

a = 34%, b = 42%, c = 20%

Passed candidates in both the subjects

= 100 – (a + b – c)

= 100 – (34 + 42 – 20) = 100 – 56 = 44%

Answer: (b)

46% of 500 = ${500 × 46}/100 = 230$

32% of 300 = ${300 × 32}/100 = 96$

Required marks = 230 – 96 = 134

Let x% of 200 = 134

${200 × x}/100 = 134$

2x = 134 ⇒ x = $134/2$ = 67%

Answer: (a)

Let the number of students in the class be 100.

Number of students in Biology = 72 and number of students in Maths = 44.

Number of students opting for both subjects = 72 + 44 – 100 = 16

Since, When 16 students opt for both subjects, total number of students = 100

When 40 students opt for both subjects,

total number of students = $100/16 × 40$ = 250

Answer: (c)

Let the total number of candidates = x

Number of candidates passed in English = 0.6x

Number of candidates passed in Maths = 0.7x

Number of candidates failed in both subjects = 0.2x

Number of candidates passed in atleast one subject

= x – 0.2x = 0.8x

0.6 x + 0.7x – 2500 = 0.8 x

1.3x – 0.8x = 2500

0.5x = 2500 ⇒ $x = 2500/0.5 = 5000$