28) Find the value of
(a) 1 + (-2) + (-3) + (-4)
(b) (-50) - (-60) + 50
(c) (-30) - 45 -- 25
29) The number of boys and girls in a school are 390 and 520 respectively. Find
the ratio of
(a) Number of girls to the number of boys.
(b) Number of boys to total number of students.
(c) Total number of students to the number of girls.
30) A rectangular hall is 80 m long and 35 m wide. Find its area and also find
the cost of tiling the hall at 24 per square metre.
OR
Find the peririeter of the following shapes.
(a) A triangle of sides 4 cm, 6 cm, 7 cm
(b) An equilateral triangle of side 9 cm.
(c) A regular pentagon with each side 8 m
Answers
28)
(a) -8
(b) 50
(c) -100
29)
30) 2800 m², ₹67,200
OR
(a) 17 cm
(b) 18 cm
(c) 40 cm
28)
(a) 1 + (-2) + (-3) + (-4) = 1 - 2 - 3 - 4
= 1 - 9
= -8
(b) (-50) - (-60) + 50 = -50 + 60 + 50
= 50 (minus and plus getting cancelled)
(c) (-30) - 45 - 25 = -30 - 70 = -100
29)
(a)
(b)
(c)
30)
Area of rectangle = l x b
= 80 x 35 = 2800 m²
Cost of tiling the hall per square metre = ₹24
Cost of tiling the hall 2800 square metre = 24 x 2800
= ₹67,200
OR
(a) Perimeter of scalene triangle
= a + b + c
= 4 + 6 + 7
= 17 cm
(b) Perimeter of equilateral triangle
= 3 a
= 3 x 9
= 18 cm
(c) Perimeter of regular Pentagon
= 5 a
= 5 x 8 = 40 cm
Answer:
28)
(a) -8
(b) 50
(c) -100
29)
(a) \frac{3}{4} (a)
4
3
(b) \frac{3}{7} (b)
7
3
(c) \frac{7}{4} (c)
4
7
30) 2800 m², ₹67,200
OR
(a) 17 cm
(b) 18 cm
(c) 40 cm
\underline\bold\red{Step-by-step\: explanation:}
Step−by−stepexplanation:
28)
(a) 1 + (-2) + (-3) + (-4) = 1 - 2 - 3 - 4
= 1 - 9
= -8
(b) (-50) - (-60) + 50 = -50 + 60 + 50
= 50 (minus and plus getting cancelled)
(c) (-30) - 45 - 25 = -30 - 70 = -100
29)
(a)
Ratio \: of \: no. \: of \: girs \: to \: the \:number \: of \: boys = \frac{390}{520} = \frac{3}{4} Ratioofno.ofgirstothenumberofboys=
520
390
=
4
3
(b)Ratio \: of \: number \: of \: boys \: to \: total \: number \: of \: students = \frac{390 }{910} = \frac{3}{7} Ratioofnumberofboystototalnumberofstudents=
910
390
=
7
3
(c)
Ratio \: of \: total \: number \: of \: students \: to \: the \: number \: of \: girls = \frac{910}{520} = \frac{7}{4} Ratiooftotalnumberofstudentstothenumberofgirls=
520
910
=
4
7
30)
Area of rectangle = l x b
= 80 x 35 = 2800 m²
Cost of tiling the hall per square metre = ₹24
Cost of tiling the hall 2800 square metre = 24 x 2800
= ₹67,200
OR
(a) Perimeter of scalene triangle
= a + b + c
= 4 + 6 + 7
= 17 cm
(b) Perimeter of equilateral triangle
= 3 a
= 3 x 9
= 18 cm
(c) Perimeter of regular Pentagon
= 5 a
= 5 x 8 = 40 cm
Step-by-step explanation:
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Warm regards:Miss Chikchiki