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Class 10 Mathematics - Chapters 1-4

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110 original MCQs with answers and worked explanations, aligned with NCERT Class 10 Mathematics: Real Numbers (20), Polynomials (30), Pair of Linear Equations in Two Variables (30), Quadratic Equations (30).

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Chapter 3: Pair of Linear Equations in Two VariablesAll chapters

30 ready questions · 10 per page

21. Chapter 3: Pair of Linear Equations in Two Variables · mcq

A farm has only chickens and goats. There are 18 heads and 50 legs in total. How many goats are there?

A.

9

B.

11

C.

7

D.

5

Show answer and explanation

7

Let chickens be cc and goats be gg. Then c+g=18c+g=18 and 2c+4g=502c+4g=50. Subtracting 2c+2g=362c+2g=36 gives 2g=142g=14, so g=7g=7.

22. Chapter 3: Pair of Linear Equations in Two Variables · mcq

Two angles are complementary. The larger is twice the smaller. What is the larger angle?

A.

30∘30^\circ

B.

45∘45^\circ

C.

120∘120^\circ

D.

60∘60^\circ

Show answer and explanation

60∘60^\circ

Complementary angles sum to 90∘90^\circ. If the smaller angle is ss, then s+2s=90∘s+2s=90^\circ, giving s=30∘s=30^\circ and the larger angle 60∘60^\circ.

23. Chapter 3: Pair of Linear Equations in Two Variables · mcq

A rectangle has perimeter 50 cm. Its length is 5 cm more than its width. What is its area?

A.

150 cm2150\text{ cm}^2

B.

100 cm2100\text{ cm}^2

C.

125 cm2125\text{ cm}^2

D.

200 cm2200\text{ cm}^2

Show answer and explanation

150 cm2150\text{ cm}^2

l+w=25l+w=25 and l−w=5l-w=5. Adding gives l=15l=15 cm, so w=10w=10 cm. The area is 15×10=150 cm215\times10=150\text{ cm}^2.

24. Chapter 3: Pair of Linear Equations in Two Variables · mcq

Two kilograms of apples and three kilograms of oranges cost ₹310. Three kilograms of apples and two kilograms of oranges cost ₹340. What is the price per kilogram of apples?

A.

₹90

B.

₹80

C.

₹50

D.

₹60

Show answer and explanation

₹80

Let prices per kilogram be a,oa,o. The equations are 2a+3o=3102a+3o=310 and 3a+2o=3403a+2o=340. Multiply by 2 and 3 respectively to get 4a+6o=6204a+6o=620 and 9a+6o=10209a+6o=1020. Hence 5a=4005a=400, so a=80a=80.

25. Chapter 3: Pair of Linear Equations in Two Variables · mcq

A boat travels at 15 km/h downstream and 9 km/h upstream. Assuming constant boat and current speeds, what is the speed of the current?

A.

9 km/h

B.

12 km/h

C.

3 km/h

D.

6 km/h

Show answer and explanation

3 km/h

Let the speed in still water be bb and current speed be cc. Then b+c=15b+c=15 and b−c=9b-c=9. Subtraction gives 2c=62c=6, hence c=3c=3 km/h.

26. Chapter 3: Pair of Linear Equations in Two Variables · mcq

A positive fraction has numerator 3 less than its denominator. Their sum is 11. What is the fraction?

A.

74\frac74

B.

38\frac38

C.

56\frac56

D.

47\frac47

Show answer and explanation

47\frac47

Let numerator be nn and denominator be dd. Then d−n=3d-n=3 and n+d=11n+d=11. These give d=7,n=4d=7,n=4, so the fraction is 4/74/7.

27. Chapter 3: Pair of Linear Equations in Two Variables · mcq

Solve 5x+2y=125x+2y=12 and 3x−2y=43x-2y=4.

A.

x=2, y=1x=2,\ y=1

B.

x=1, y=2x=1,\ y=2

C.

x=2, y=−1x=2,\ y=-1

D.

x=3, y=−2x=3,\ y=-2

Show answer and explanation

x=2, y=1x=2,\ y=1

Adding the equations eliminates yy: 8x=168x=16, so x=2x=2. Then 10+2y=1210+2y=12, giving y=1y=1.

28. Chapter 3: Pair of Linear Equations in Two Variables · mcq

For which value of m is the pair mx+y=4mx+y=4 and x−y=2x-y=2 inconsistent?

A.

2

B.

-1

C.

0

D.

1

Show answer and explanation

-1

For m=−1m=-1, the first equation becomes −x+y=4-x+y=4, or x−y=−4x-y=-4, which contradicts x−y=2x-y=2. For other m the coefficient determinant −m−1-m-1 is nonzero.

29. Chapter 3: Pair of Linear Equations in Two Variables · mcq

If (x,y)=(2,3)(x,y)=(2,3) satisfies x+ky=11x+ky=11, what is k?

A.

4

B.

5

C.

3

D.

2

Show answer and explanation

3

Substitute x=2,y=3x=2,y=3: 2+3k=112+3k=11. Thus 3k=93k=9 and k=3k=3.

30. Chapter 3: Pair of Linear Equations in Two Variables · mcq

For a1x+b1y+c1=0a_1x+b_1y+c_1=0 and a2x+b2y+c2=0a_2x+b_2y+c_2=0, with nonzero a2,b2,c2a_2,b_2,c_2, which condition guarantees a unique solution?

A.

a1a2=b1b2=c1c2\frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}

B.

a1a2=b1b2≠c1c2\frac{a_1}{a_2}=\frac{b_1}{b_2}\ne\frac{c_1}{c_2}

C.

The two equations are identical

D.

a1a2≠b1b2\frac{a_1}{a_2}\ne\frac{b_1}{b_2}

Show answer and explanation

a1a2≠b1b2\frac{a_1}{a_2}\ne\frac{b_1}{b_2}

A unique solution occurs when a1b2−a2b1≠0a_1b_2-a_2b_1\ne0, equivalent to unequal ratios a1/a2a_1/a_2 and b1/b2b_1/b_2. The lines then intersect at exactly one point.