Question

A flat-bottomed test tube loaded with some lead shots, was found to weigh 30 gf. The test tube floats upright on the surface of water with 15 cm of its length immersed. The same test tube when floated in kerosene was found to float with 20 cm immersed. Calculate the R.D. of kerosene.​

Answer 1

Answer:

Solution−

Given that,

lf a box of sweets is divided among 24 children, they will get 5 sweets each.

Now, we have to find, how many would each get, if the number of the children is reduced by 4.

As number of children decreases, the share in sweets increases.

So, it means, number of sweets and number of children are in inverse variation.

Now, Number of children = 24 - 4 = 20

Let assume that each children get x number of sweets

So,

\begin{gathered}\begin{array}{|c|c|c|c} \hline \rm Number \: of \: children&\rm 24&\rm 20 \\ \hline\rm Number \: of \:sweets&\rm 5&\rm x \\ \hline \end{array} \\\end{gathered}

Numberofchildren

Numberofsweets

24

5

20

x

By definition of inverse variation,

\begin{gathered}\rm \: 24 \times 5 = 20 \times x \\ \end{gathered}

24×5=20×x

\begin{gathered}\rm \: x = \dfrac{24 \times 5}{20} \\ \end{gathered}

x=

20

24×5

\begin{gathered}\rm\implies \:x = 6 \\ \end{gathered}

⟹x=6

Hence, each children would get 6 sweets.

\rule{190pt}{2pt}

Basic Concept Used :-

Inverse Variation or Indirect variation :- If x and y are two variables, then x and y are said be in inverse variation, if x increases then y decreases or x decreases if y increases. That means x and y change in the same ratio but inversely.