Question

1)The product of two decimals is 1.8576. If one of the decimal is 0.54, then the other decimal is
(A) 2.44 (B) 1.34
(C) 3.44 (D)8.65
2)A vehicle covers a distance of 43.2 km in 2.4 liters of petrol. Then the distance will it travel in 1 liter of petrol is
(A) 12 km (B) 18 km
(C) 20 km (D) 21 km
3). Each side of a regular polygon is 2.5 cm in length. The perimeter of the polygon is 12.5 cm. then the number of sides of the polygon is.
(A) 5 (B) 6
(C) 4 (D)7
4) In a school 45 of the students are boys. If there are 200 girls, then the number of boys in the
school is.
(A) 600 (B) 800
(C) 5000 (D)100

Answer 1

1 ). Let the other decimal be x.

So, x * 0.54 = 1.8576

x = 1.8576 / 0.54

x = 18576 / 5400 = 86 / 25 = 3.44

=> Other decimal is 3.44 ( option C ).

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2 ). Distance = 43.2 km

Petrol = 2.4 l

Distance travelled in 2.4 l of petrol = 43.2 km

Distance travelled in 1 l of petrol = 43.2 / 2.4

=> 432 / 24 = 18 km ( option B )

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3 ). Length of each side of polygon = 2.5 cm.

Perimeter of the polygon = 12.5 cm

Number of sides of polygon = Perimeter / Length of each side.

No. Of sides => 12.5 / 2.5 = 125 / 25 = 5

=> 5 sides ( option A )

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4 ). Number of girls = 200

Let total number of students be x.

ATQ, 4/5 of the students are boys.

Number of boys = 4x /5

Total Number of boys + Total number of girls = total no. Of students in the school

4x / 5 + 200 = x

4x / 5 - x = - 200

( 4x - 5x ) / 5 = - 200

- x / 5 = - 200

x = 200 * 5 = 1000

Total number of students = x = 1000

Number of boys = 4 x / 5 = 4 * 1000 / 5

=> 800

So, Number of boys = 800 ( option B ).