If $$a^2 + 4b^2 = 4ab$$, then a : b = ?​

If the mean proportional of A and 27 is 18, then find the value of A.

A typist takes 40 minutes to type 2 pages. How long (in minutes) will he take to type 110 pages?

Find the value of x in the proportion 69 : 23 :: 63 : x.

The ratio of the incomes of A and B is 3 : 5 and the ratio of their expenditures is 2: 3. If the income of A is equal to 6/7 of the expenditure of B, then the ratio of the savings of A and B is :

The ratio of number of boys and girls in a school of 3528 students is 5:4. How many more girls should be admitted in the school to make this ratio 1:1?

If the third proportional of 28 and 70 be x, then what is the value of x?

The cost of 40 packets of 12 pens is ₹1680. The cost of 30 packets each containing 9 pens is

The first, second and fourth numbers in a proportion are 31, 12 and 156 respectively.