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Find the value of x if 45% of marks x is 405. - Mathematics

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Question

Find the value of x if 45% of marks x is 405.

Sum

Solution

Given, 45% of marks x is 405

∴ `45/100 xx x` = 405

⇒ x = `(405 xx 100)/45`

⇒ x = 900 marks

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Chapter 7: Comparing Quantities - Exercise [Page 205]

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NCERT Exemplar Mathematics [English] Class 7
Chapter 7 Comparing Quantities
Exercise | Q 80. (iv) | Page 205

Video TutorialsVIEW ALL [1]

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When you design your healthy diet, you want to make sure that you meet the dietary requirements to help you grow into a healthy adult. As you plan your menu, follow the following guidelines

  1. Calculate your ideal weight as per your height from the table given at the end of this question.
  2. An active child should eat around 55.11 calories for each kilogram desired weight.
  3. 55 per cent of calories should come from carbohydrates. There are 4 calories in each gram of carbohydrates.
  4. 15 per cent of your calories should come from proteins. There are 4 calories in each gram of proteins.
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Following is an example to design your own healthy diet.

Example

  1. Ideal weight = 40 kg.
  2. The number of calories needed = 40 × 55.11 = 2204.4
  3. Calories that should come from carbohydrates = 2204.4 × 0.55 = 1212.42 calories.
    Therefore, required quantity of carbohydrates = `1212.42/4` = 303.105 g = 300 g. (approx)
  4. Calories that should come from proteins = 2204.4 × 0.15 = 330.66 calories.
    Therefore, required quantity of protein = `330.66/4` g = 82.66 g.
  5. Calories that may come from fat = 2204.4 × 0.3 = 661.3 calories.
    Therefore, required quantity of fat = `661.3/9` g = 73.47 g.

Answer the Given Questions

  1. Your ideal desired weight is ______ kg.
  2. The quantity of calories you need to eat is ______.
  3. The quantity of protein needed is ______ g.
  4. The quantity of fat required is ______ g.
  5. The quantity of carbohydrates required is ______ g.
Ideal Height and Weight Proportion
Men Women
Feet cm Kilograms Feet cm Kilograms
5’ 152 48 4’7” 140 34
5’1” 155 51 4’8” 142 36
5’2” 157 54 4’9” 145 39
5’3” 160 56 4’1” 147 41
5’4” 163 59 4’11” 150 43
5’5” 165 62 5’ 152 45
5’6” 168 65 5’1” 155 48
5’7” 170 67 5’2” 157 50
5’8” 173 70 5’3” 160 52
5’9” 175 73 5’4” 163 55
5’10” 178 75 5’5” 165 57
5’11” 180 78 5’6” 168 59
6’ 183 81 5’7” 170 61
6’1” 185 84 5’8” 173 64
6’2” 188 86 5’9” 175 66
6’3” 191 89 5’10” 178 68
6’4” 193 92 5’11” 180 70

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