Multiply the given in question.

Correct Option: C

Multiply the given in question.
The answer would be
? = 10.8 x 5.5 x 8.4 = 498.96

Solve it by simple mathematics rule.

Correct Option: E

8648 - 7652 = ? x 40
996 = ? x 40 ⇒ ? = 996/40 = 24.9

? = 683.46 - 227.39 - 341.85
= 683.46 - 569.24 = 114.22

Correct Option: A

? = 683.46 - 227.39 - 341.85
= 683.46 - 569.24 = 114.22

Solution 1.
Let the question solved correctly by Mohan = X ;
and number of question solved wrongly by Mohan = 30 - X ;
According to the question,
3X - (30 - X) x 2 = 40

Solution 2.
Let the question solved correctly by Mohan = X ;
and number of question solved wrongly by Mohan = Y ;
According to given question;
X + Y = 30 ; and 3X - 2Y = 40 ;

Correct Option: D

Solution 1.
Let the question solved correctly by Mohan = X ;
and number of question solved wrongly by Mohan = 30 - X ;
According to the question,
3X - (30 - X) x 2 = 40
⇒ 3x - 60 + 2x = 40
⇒ 5x - 60 = 40
⇒ 5x = 40 + 60 ⇒ x = 100/5 = 20
∴ Mohan attempted 20 questions correctly .

Solution 2.
Let the question solved correctly by Mohan = X ;
and number of question solved wrongly by Mohan = Y ;
According to given question;
X + Y = 30 ; -----------i
3X - 2Y = 40 ;-------ii

Now multiply the first equation by 2;
we will get
2X + 2Y = 60 ;--------iii
After Add the equation ii and iii , we will get
3X - 2Y + 2X + 2Y = 40 + 60 ;
⇒ 5X = 100 ;
⇒ X = 20;

∴ Mohan attempted 20 questions correctly .

Let the maximum marks = x.
According to the question,
40x/100 = 200 + 8

Correct Option: A

Let the maximum marks = x.
According to the question,
40x/100 = 200 + 8
⇒ x = 208 x 10/4 = 520