Brain Grain · braingrain.in
Maths — Practice Paper · Set 1
Part I — Short Answer Questions 18 × 2 = 36
Answer briefly. (Answer all questions.)
1.Find the following squares using one of the above identities. Determine which of these identities will make these calculations easier. (i) $117^2$ (ii) $78^2$ (iii) $198^2$ (iv) $214^2$ (v) $1104^2$ (vi) $1120^2$[2]
2.The ratio of the perimeters of two circles is $5:4$ . What is the ratio of their radii?[2]
3.When a single 6-sided die is rolled, what is the total number of possible outcomes in the sample space?[2]
4.Fig. 8.12 shows Stages 0 to 3 of the Sierpiński square carpet. Stage 0 of this fractal is a square sheet of paper. To construct Stage 1, each side of the square is trisected and the points of trisection of opposite sides are joined to obtain nine smaller squares. The centre square is then removed and the 8 smaller squares are retained, leaving a square hole in the centre. The same process is repeated on the eight smaller shaded squares to obtain Stage 2 and so on. (i) How many red squares are there in Stages 0 to 3? (ii) Can you predict the number of red squares in Stages 4 and 5? (iii) Can you find a rule for the number of red squares at the nth stage? Write the explicit formula as well as the recursive formula for the number of red squares at any stage. (iv) Suppose the area of the square in Stage 0 is 1 square unit. What is the area of the red region in Stages 1, 2 and 3? What will be the area of the red region in Stages 4 and 5? Find the explicit as well as the recursive formula for the area of the red region at the nth stage. What happens to this area as n, the number of stages, goes on increasing?[2]
5.Find 5 rational numbers between $\dfrac{1}{6}$ and $\dfrac{2}{5}$ .[2]
6.An isosceles triangle has perimeter 30 cm and each of the equal sides is 12 cm. Find the area of the triangle.[2]
7.In a circle, a chord is 5 cm away from the centre. If the radius of the circle is 13 cm, what is the length of the chord?[2]
8.Suppose the length of a rectangular box is 7 cm and breadth is 11 cm. Find the volume if the height is (i) 5 cm, (ii) 9 cm, (iii) 13 cm. Find the linear pattern representing the volume of the rectangular box.[2]
9.Without performing long division, determine which of the following rational numbers will have terminating decimals and which will be repeating: $\dfrac{7}{20}$ , $\dfrac{4}{15}$ and $\dfrac{13}{250}$ . Then check your answers by explicitly performing the long divisions and expressing these rational numbers as decimals.[2]
10.Find a GP for which the sum of the first two terms is $-4$ and the fifth term is 4 times the third term.[2]
11.When two chords intersect, each of them is divided into two line segments. Show that if the intersecting chords are of equal length, then the line segments of one chord are equal to the corresponding line segments of the other chord.[2]
12.A traffic signal board, indicating 'SCHOOL AHEAD', is an equilateral triangle with side 'a'. Find the area of the signal board, using Heron's formula. If its perimeter is 180 cm, what will be the area of the signal board?[2]
13.Find the perimeter of a sector (i.e., the curved portion as well as the two straight portions) of a circle of radius 14 cm and sector angle 75°.[2]
14.The sum of the first three terms of a geometric progression is 26, and the sum of their squares is 364. Find the terms of the GP.[2]
15.Find the quotient: (i) $\dfrac{2}{3}\div\dfrac{3}{10}$ (ii) $\dfrac{7}{11}\div\dfrac{5}{8}$ (iii) $-\dfrac{4}{7}\div\dfrac{5}{14}$[2]
16.A chord of a circle is equal to the radius of the circle. Find the angle subtended by the chord at a point on the minor arc and also at a point on the major arc.[2]
17.If the wheel of a bicycle has a diameter of 60 cm, find how far a cyclist will have travelled after the wheel has rotated 100 times.[2]
18.Sarita is reading a book of 500 pages. She reads 20 pages every day. How many pages will be left after 15 days? Express this as a linear pattern.[2]
🔑 Show Answer Key — Set 1
- 1. (i) $13689$ (ii) $6084$ (iii) $39204$ (iv) $45796$ (v) $1218816$ (vi) $1254400$
- 2. The ratio of their radii is $5:4$ .
- 3. There are $6$ possible outcomes: $\{1,2,3,4,5,6\}$ .
- 4. (i) Stages 0 to 3 have $1,8,64,512$ red squares. (ii) Stages 4 and 5 have $4096$ and $32768$ red squares. (iii) If Stage 0 is counted as $n=0$ , the number of red squares is $R_n=8^n$ ; recursively, $R_0=1$ and $R_n=8R_{n-1}$ for $n\geq1$ . (iv) Red areas for Stages 1, 2, 3 are $\dfrac89,\dfrac{64}{81},\dfrac{512}{729}$ . For Stages 4 and 5 they are $\dfrac{4096}{6561}$ and $\dfrac{32768}{59049}$ . Explicitly, $A_n=\left(\dfrac89\right)^n$ ; recursively, $A_0=1$ and $A_n=\dfrac89A_{n-1}$ . As n increases, the area approaches 0.
- 5. Five examples are $\dfrac{6}{30}$ , $\dfrac{7}{30}$ , $\dfrac{8}{30}$ , $\dfrac{9}{30}$ and $\dfrac{10}{30}$ .
- 6. $9\sqrt{15}\text{ cm}^2$ , approximately $34.9\text{ cm}^2$ .
- 7. The chord length is $24$ cm.
- 8. (i) $385\text{ cm}^3$ (ii) $693\text{ cm}^3$ (iii) $1001\text{ cm}^3$ The linear pattern is $V=77h$ , where $h$ is the height in cm.
- 9. $\dfrac{7}{20}$ terminates: $0.35$ . $\dfrac{4}{15}$ is non-terminating repeating: $0.2\overline{6}$ . $\dfrac{13}{250}$ terminates: $0.052$ .
- 10. Two possible GPs are $-\dfrac{4}{3},-\dfrac{8}{3},-\dfrac{16}{3},\ldots$ and $4,-8,16,-32,64,\ldots$ .
- 11. Let equal chords AB and CD intersect at P. Then $AP+PB=CP+PD$ because $AB=CD$ . Also, by the intersecting chords theorem, $AP\cdot PB=CP\cdot PD$ . Two positive segment-pairs with the same sum and same product are the same pair of numbers. Therefore the two segments of one chord are equal to the corresponding two segments of the other chord.
- 12. The area is $\dfrac{\sqrt3}{4}a^2$ . If the perimeter is $180$ cm, the area is $900\sqrt3\text{ cm}^2$ .
- 13. $\dfrac{139}{3}$ cm, i.e. about $46.3$ cm.
- 14. The terms are $2,6,18$ or $18,6,2$ .
- 15. (i) $\dfrac{20}{9}$ (ii) $\dfrac{56}{55}$ (iii) $-\dfrac{8}{5}$
- 16. At a point on the minor arc: $150^\circ$ ; at a point on the major arc: $30^\circ$ .
- 17. $\dfrac{132000}{7}$ cm, i.e. about $188.6$ m.
- 18. After 15 days, $200$ pages will be left. The linear pattern is $P=500-20d$ , where $P$ is the number of pages left after $d$ days.