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If `a/b = c/d = e/f`, prove that `(ab + cd + ef)^2 = (a^2 + c^2 + e^2) (b^2 + d^2 + f^2)`.
Concept: undefined >> undefined
If `a/b = c/d = r/f`, prove that `((a^2b^2 + c^2d^2 + e^2f^2)/(ab^3 + cd^3 + ef^3))^(3/2) = sqrt((ace)/(bdf)`
Concept: undefined >> undefined
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If a, b, c, d are in continued proportion, prove that:
`sqrt(ab) - sqrt(bc) + sqrt(cd) = sqrt((a - b + c) (b - c + d)`
Concept: undefined >> undefined
If a, b, c, d are in continued proportion, prove that:
(a2 + b2 + c2) (b2 + c2 + d2) = (ab + bc + cd)2.
Concept: undefined >> undefined
If `x/a = y/b = z/c`, show that `x^3/a^3 - y^3/b^3 = z^3/c^3 = (xyz)/(zbc).`
Concept: undefined >> undefined
If `x/a = y/b = z/c`, prove that `x^3/a^2 + y^2/b^2 + z^3/c^2 = ((x + y + z)^3)/((a + b ++ c)^2)`.
Concept: undefined >> undefined
If `a = (b + c)/(2), c = (a + b)/(2)` and b is mean proportional between a and c, prove that `(1)/a + (1)/c = (1)/b`.
Concept: undefined >> undefined
Using a graph paper, drawn an Ogive for the following distribution which shows a record of the weight in kilograms of 200 students.
| Weight | Frequency |
| 40 - 45 | 5 |
| 45 - 50 | 17 |
| 50 - 55 | 22 |
| 55 - 60 | 45 |
| 60 - 65 | 51 |
| 65 - 70 | 31 |
| 70 - 75 | 20 |
| 75 - 80 | 9 |
Use your ogive to estimate the following:
(i) The percentage of students weighing 55kg or more.
(ii) The weight above which the heaviest 30% of the students fall.
(iii) The number of students who are:
(1) under-weight and
(2) over-weight, if 55·70 kg is considered as standard weight.
Concept: undefined >> undefined
The frequency distribution of scores obtained by 230 candidates in a medical entrance test is as ahead:
| Cost of living Index | Number of Months |
| 400 - 450 | 20 |
| 450 - 500 | 35 |
| 500 - 550 | 40 |
| 550 - 600 | 32 |
| 600 - 650 | 24 |
| 650 - 700 | 27 |
| 700 - 750 | 18 |
| 750 - 800 | 34 |
| Total | 230 |
Draw a cummulative polygon (ogive) to represent the above data.
Concept: undefined >> undefined
Use graph paper for this question. The following table shows the weights in gm of a sample of 100 potatoes taken from a large consignment:
| Weight (gms) | Frequency |
| 50 - 60 | 8 |
| 60 - 70 | 10 |
| 70 - 80 | 12 |
| 80 - 90 | 16 |
| 90 - 100 | 18 |
| 100 - 110 | 14 |
| 110 - 120 | 12 |
| 120 - 130 | 10 |
(i) Calculate the cumulative frequencies.
(ii) Draw the cumulative frequency curve and form it determine the median weights of the potatoes.
Concept: undefined >> undefined
Find the value of x in the following proportions : 10 : 35 = x : 42
Concept: undefined >> undefined
Find the value of x in the following proportions : 3 : x = 24 : 2
Concept: undefined >> undefined
Find the value of x in the following proportions : 2.5 : 1.5 = x : 3
Concept: undefined >> undefined
Find the value of x in the following proportions : x : 50 :: 3 : 2
Concept: undefined >> undefined
Find the fourth proportional to 3, 12, 15
Concept: undefined >> undefined
Find the fourth proportional to `(1)/(3), (1)/(4), (1)/(5)`
Concept: undefined >> undefined
Find the fourth proportional to 1.5, 2.5, 4.5
Concept: undefined >> undefined
Find the fourth proportional to 9.6 kg, 7.2 kg, 28.8 kg
Concept: undefined >> undefined
Find the third proportional to 5, 10
Concept: undefined >> undefined
Find the third proportional to 0.24, 0.6
Concept: undefined >> undefined
