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Question 91.by reduction of rupee 1 per kg in the price of onion, beena can buy one kg onion more for Rs.56. find the original price of the onion per kg? by Bharat Jain, answered on November 16, 2007 at 10:28 p.m. I.S.T.
Answer 91. Let price per kg.of onion is Rs. x + 1
According to question   
                                           56 / x  - 56 / (x + 1)   =  1
                              or          56(x  + 1 -  x) / (x^2 +  x)  = 1
                              or          x^2 + x - 56 = 0
                              or          (x + 8) (x - 7) = 0
                              or          x = -  8, x = 7
                    Therefore price per kg.of onion is Rs (7 + 1 ) = Rs. 8
Question 92. Sum, Product or Difference of two integers is an integer. What is this property called? by Ram Prakash answered on Nov 18, 2007 at 9:49 p.m. I.2×S.T.
Answer 92. Closure Property.
Question 93. Does closure property in case of integers exist for division?
By Rekha Bakshi Answered on Nov 19, 2007 at 9:53 pm. I.S.T.
Answer 93. No. Example 3, 4 are integers but 3/4 is not integer.
Question 94.can we add the numders when both of them have roots for eg
12root7+3root7 by sarah siddiqua answers on Nov 20, 2007 at 10;01 p.m. I.S.T.
Answer 94. Yes. 12 square root7+3 square root7 = 10 square root7, but 12 square root 7 and 3 cube root 7 cannot be added.
Question 95. Two third of a consignment was sold at a profit of 5% and the remainder at a loss of 2%. If the total profit was Rs 400. Find the value of the consignment.By Abhishek,answered on Nov 22, 2007 at  10:18 p.m.
Answer 95. Let the value of the consignment be Rs y
                Profit on 2/3 of consignment =  Rs (5×2×y)/(100×3) = Rs 10y/300
                Loss on 1/3 of consignment  =  Rs (1×y×2)/(3×100) = Rs  2y/300
                according to problem
                10y/300  -  2y/300 = 400
     (×300)  10y - 2y = 120000
          or    8y         = 120000
          or     y          = 120000/8
          or     y          = 15000
Therefore value of the consignment = Rs 15000


Question 96. Sir ,this is a question from the model paper.which term of the sequence 114,109,104... is the first negative term.I got a bit confused.help me sir. by Sowmya, answered on Nov 24, 2007 at 5:52 p.m.
Answer 96. 109 - 114 = 104 - 109 = - 5.
                 Therefore given sequence is an A.P.
                 First term (a) = 114
                 Common difference (d) = - 5
                 For finding first negative term
                 Tn < 0
                 a + (n - 1)d < 0
                 114 + (n - 1)(- 5) < 0
            or   114 - 5n + 5 < 0
            or   119 - 5n < 0
            or   - 5n < - 119
            or   5n > 119
            or   n > 119/5
                  n > 23.8
                  Therefore first negative term is 24
Question 97.mayank made a bird bath for his garden in the shape of a cylinder with a hemispherical depression at on end. the height of the cylinder is 1.45 m and its radius is 30 cm. find the total surface area of the bird bath. by Priyanka Arora , answered on Nov 25, 2007 at 4:57 p.m
Answer 97. Total Surface area (assuming that base is open)
                = C.S.A. of cylinder  +  C.S.A. of hemisphere
                = 2(pie)rh + 2(pie)r^2
                    = 2(pie)r(r+h)
                = 2 × 22/7 × 30 (145 + 30)
                = 33000 square cm.
Question 98. Sir we need answers to CBSE Model Sample papers 1,2 and 3. When will we get the answers? by Sunanda answered on Nov 27, 2007 at 8:38 p.m.
Answer 98. The answers will be provided during the next month.
Question 99. x = 3 is a line parallel to _______________ axis? by Jagnoor Singh class 1X, answered on Nov 28, 2007 at 11:50 p.m.
Answer 99. x = 3 is parallel to y axis



Question.100  If the 4th term is twice the 8th term,prove that the 10th term is twice the 11th term. By sumaira, answered on
Nov 30,2007 at 7:31 pm, I.S.T.
Answer 100 T4 = 2 (T8)
                  a + 3d = 2 (a+7)
                  a + 3d = 2a + 14d
             or   a + 11 d = 0
             or  a = - 11d           ............(1)
                 T10 = a + 9d
                       = - 11d + 9d            using (1)
                       = - 2d
             2(T11) = 2(a + 10d)
                       = 2(- 11d + 10d)       using (1)
                       = 2 (-d)
                       = -2d
   Therefore T10 = 2(T11)
Question.101 If two equal chords of a circle intersect within the circle, prove that segments of one chord ar equal to the corresponding segments of the other chord, by Harvinder Singh, answered on Dec 02, 2007 at 9:11 p.m.
Answer 101.   Download Answer
Question.102 Lines AB and CD are parllel and P is any point between the two lines . Prove that angle ABP +angle CDP = angle DPB, by Gagandeep singh, answered on Dec 4, 2007 at 9:51 p.m.
Answer 102.   Download Answer
Question.103  A cylinder, a cone and a hemisphere have equal base and height. Find ratio of their volumes. by V. Anusha, answered on Dec 08, 2007 at 9:00 p.m. I.S.T.
Answer 103. Since they have equal base therefore their radii are equal.
                   Let each radius = x
                   Height of hemisphere is equal to  its radius
                   Therefore  height of each is = x
                   volume of cylinder : volume of cone : volume of hemisphere = pie r^2 h : 1/3  pie r^2 h : 2/3 pie r^3
                                                                                                   =  h : 1/3 h : 2/3 r
                                                                                                   =  x : 1/3 x : 2/3 x
                                                                                                   =  1 : 1/3 : 2/3
                                                                                                   =  3 : 1 : 2
Question.104  If a  student  had  walked  1km/hr  faster ,he would  have taken  15  minutes  less  to  walk  3km.find  the  rate  at  which  he  was  walking. by Rupashree, answered on Dec 12, 2007 at 8:07 p.m.
Answer 104. Let original speed of walking = x km/h
                   according to problem
                   3/x  -   3/(x + 1)  =  15/60         [ since time = distance/speed]
           or      3 [1/x - 1/(x+1)] = 1/4
           or      3(x+1 - x)/(x^2 + x) = 1/4
           or      3/(x^2 + x) = 1/4
           or      x^2 + x = 12
           or      x^2 + x - 12 = 0
           or      (x + 4)(x - 3) = 0
           or      x = - 4, x = 3
                   original speed of walking = 3 km/h
Question.105 How many balls, each of radius 0.5cm, can be made from a solid sphere of metal of radius 10cm by melting the sphere? by keerthanaa, answered on Dec 14, 2007 at 7:49 p.m.
Answer 105. No. of balls = Volume of metal sphere / Volume of a spherical ball
                                  =  (4/3 pie R^3)/(4/3 pie r^3)  (where R is radius of sphere and r is radius of a ball)
                                  =  R^3/ r^3
                                  =  10×10×10 / 0.5×0.5×0.5
                                  =  8000

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