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   cbsemath.com -  the no. 1 CBSE Math site   cbsemath.com - in the service of student community
Question 196.  Solve for x and y:   10x+4y =3040  and  4x + 10y =765.50 by Aaradhna Tyagi, M.P.S, Ghaziabad. Answered on 05 Jan 2009 at 6:06 p.m.
Answer 196. 10x + 4y = 3040 ......... (i)
                     4x + 10y = 765.5  .......(ii)
                      (i) × 5 - (ii) × 2
                      50x + 20y = 15200
                      8x + 20y = 1531
                       -      -           -
______________________________________
                        42x = 13669
                or         x = 13669/42
                Substituting in (ii)
                      27338/21 + 10y = 765.5
                or   10y = - 11262.5/21
                         y = - 1126.25/21
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Question 197. In a frequency distribution, the mid value of a class is 10 and the width of the class is 8. The lower limit of the class is :   (a) 6         (b) 7       (c) 8        (d) 12. By Rajendra. Answered on 7 March 2010 at 12:48pm.
Answer 197.  Class Size = 8. Therefore Lower Limit = Mid Value - 8/2
                                                                        = 10 - 4
                                                                        = 6
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Question 198. define linear equation in one variable, by Dhruv Patel, Patan. Answered on 13 April 2010 at 7:57 p.m. IST.
Answer 198. An equation of the form ax + b = 0, where a, b are real numbers and a is not equal to zero.
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Question 199. What is the approximate date of cbse class 10 result for exams held in 2010? By Shivam Jain, St. Josephs Convent Sec School , Bathinda. Answered on 13 April 2010 at 8:06 p.m. I.S.T.
Answer 199. The approximate date of CBSE Results 2010 for class X is between 25 May to 30 may 2010. For more information visit our Results site here
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Question 200. Represent root 2 in a number line? By Niraj Kumar Das, D A V Public School, Sambalpur. Answered on 13 April 2010 at 8:33 p.m. I.S.T.
Answer 200.

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   cbsemath.com -  the no. 1 CBSE Math site   cbsemath.com - in the service of student community
Question 201. If cos A = 25. Find sin A, by shubham kumar dwivedi, a.b.p.school,  Renukoot ,UP. Answered on 13 April 2010 at 8:43 p.m. I.S.T.
Answer 201.
cos A = 1/ 25
cos2 A = 1/ 25 × 25
cos2 A = 1/ 625
1 - sin2 A =1/ 625
sin2 A = 1 - 1/ 625
sin2 A = 624/ 625
sin A = + - (square root 624)/ 25
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Question 202. A cylinder and a cone have the same base and height .The ratio of their volumes  is ( in same order ), by Neha Pani, Ghanshyam Hemlata Vidya Mandir, Jharsuguda. Answered on 13 April 2010 at 8:59 p.m. I.S.T.
Answer 202. 3:1 [ volume of cylinder = pie r2 h and volume of cone = 1/3 pie r2 h]
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Question 203. Aftab tells his daughter,"7 years ago i was 7 times as old as you were then".Also 3 years from now, i shall be 3 times as old as you will be." represent this situation algebraically [solved],by soumya puli, k.V.Picket, Hyderabad. Answered on 27 June 2010 at 10:49 p.m. I.S.T.
Answer 203.              Let Daughter's age 7 years ago = x
                              Aftabs's age 7 years ago = y
acc. to condition I      y = 7x                        ...........(i)
acc. to condition II     y + 10 = 3 (x + 10)
                               y - 3x = 20                 ............(ii)
                               From i and ii
                               7x - 3x = 20
                               4x = 20
                                x = 5
                                substituting in i
                                y = 35
                                Daughters present age = 12 years
                                Aftab's present age =      42 years
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Question 204. Solve the linear equation by subsitution method x+y=14 , x-y=4, by Harmunjot Kaur Tiwana, Shivalik Public School, Mohali. Answered on 27 June 2010 at 10:58 p.m. I.S.T.
Answer 204. x + y = 14  .........(i)
                  x - y = 4    .........(ii)
            or   x = 4 + y  ..........(iii)
                 Substituting in (i)
                  4 + y + y = 14
            or    2y = 10
            or    y = 5
                  Substituting in (iii)
                   x = 4 + 5
                   x = 9
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Question 205. A circular pipe with an inside diameter of six feet can carry a certain amount of water. How many circular pipes with an inside diameter of 1 inch will be needed to carry the same amount of water?
Answer 205. Radius of bigger pipe = 3 feet = 36 inch
                  Radius of small pipe = 0.5 inch
                  No. of pipes = (36×36)/ (0.5×0.5)
                                   = 5184
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