If a sum of ₹ x is divided between A and B in the ratio $\dfrac{a}{b} : \dfrac{c}{d}$, then A gets:

1. ₹$\Big(\dfrac{abx}{ac + bd}\Big)$

2. ₹$\Big(\dfrac{abx}{ad + bc}\Big)$

3. ₹$\Big(\dfrac{adx}{ad + bc}\Big)$

4. ₹$\Big(\dfrac{adx}{ab + cd}\Big)$

The ratio of the number of boys and girls in a school of 720 students is 7 : 5. How many more girls should be admitted to make the ratio 1 : 1?

1. 90

2. 120

3. 220

4. 240

What must be subtracted from each of 7, 9, 11 and 15, so that the resulting numbers are in proportion?

1. 1

2. 2

3. 3

4. 5

If p, q, and r are in continued proportion, then :

1. p : q = p : r

2. q : r = p² : q²

3. p : q² = r : p²

4. p : r = p² : q²