1.  The cost of levelling a rectangular field at the rate of 85 paise per square metre is rs.624.75.find the perimeter of the field if its sides are in ratio of 5:3?
  2. The perimeter of one square is 748cm and that of another is 336cm.Find the perimeter and the diagonal of a square which is equal in area to these two?
  3. A closed tea chest is 47cm long,47cm wide and 60 cm by internal measurement.Find in square metresthe total area of tinfoil needed for lining it?
  4. An open tin box 21 cm long,9 cm wide,8 cm high is fitted with a tin lid which overlaps to a depth of 1 cm all round. What is the total area of tin sheeting used for the box and the lid?

Asked by lakhwindersaggu2 | 15th Feb, 2017, 07:30: PM

Expert Answer:

begin mathsize 16px style 1. space Given space that space the space sides space are space in space the space ratio space 5 space colon space 3. space So comma space the space length space and space breadth space of space the space rectangle space are space 5 straight x space and space 3 straight x space respectively. space Area space equals space length space cross times space breadth space equals space 5 straight x space cross times space 3 straight x space equals space 15 space straight x to the power of 2 space end exponent According space to space the space given space condition comma 15 space straight x to the power of 2 space end exponent cross times space 85 over 100 equals 624.75 rightwards double arrow space straight x to the power of 2 space end exponent equals fraction numerator 624.75 cross times 100 over denominator 15 space cross times space 85 end fraction equals 49 rightwards double arrow space straight x equals plus-or-minus 7 Since space dimensions space of space the space rectangle space cannot space be space negative comma space so comma space straight x equals 7 So comma space the space length space equals space 5 left parenthesis 7 right parenthesis space equals space 35 space straight m space and space the space breadth space equals space 3 left parenthesis 7 right parenthesis space equals space 21 space straight m perimeter space equals space 2 left parenthesis length space plus breadth right parenthesis space equals space 2 left parenthesis 35 space plus space 21 right parenthesis space equals 112 space straight m 2. space space Perimeter space of space square space 1 space equals space 748 space cm rightwards double arrow 4 straight s equals 748 rightwards double arrow straight s 1 equals 187 space cm Perimeter space of space square space 2 space equals space 336 space cm rightwards double arrow 4 straight s equals 336 rightwards double arrow straight s 2 equals 84 space cm So comma space combined space area space of space the space two space squares space equals space left parenthesis 187 right parenthesis squared plus left parenthesis 84 right parenthesis squared equals straight c space sq. space cm left parenthesis new space square space side right parenthesis squared equals 42025 rightwards double arrow new space square space side equals 42025 equals 205 space cm So comma space perimeter space of space resultant space square space equals space 4 left parenthesis 205 right parenthesis equals 820 space cm diagonal space of space the space square equals space square root of 2 left parenthesis side right parenthesis equals square root of 2 cross times 205 equals 205 left parenthesis 1.414 right parenthesis space cm space... left parenthesis Taking space square root of 2 equals 1.414 right parenthesis rightwards double arrow diagonal space of space the space square equals 289.87 space approx Dear space student space straight I space have space solved space two space out space of space the space 4 space queries. space But space kindly space post space only space 1 space query space at space straight a space time. end style

Answered by Rebecca Fernandes | 15th Feb, 2017, 08:59: PM

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