Exams

A sinkhole (in Karst topography) is a hole in the ground that forms when water dissolves surface rock. Often, this surface rock is limestone, which is easily eroded, or worn away, by the movement of water.

Formation of a Sinkhole: In a landscape where limestone sits underneath the soil, water from rainfall collects in cracks in the stone. These cracks are called joints. Slowly, as the limestone dissolves and is carried away, the joints widen until the ground above them becomes unstable and collapses. The collapse often happens very suddenly and without very much warning. Water collects in these collapsed sections, forming sinkholes.

Sinkholes also form when the roofs of caves collapse. Sinkholes are often funnel-shaped, with the wide end open at the surface and the narrow end at the bottom of the pool.Sinkholes vary from shallow holes about 1 meter (3 feet) deep, to pits more than 50 meters (165 feet) deep.

At 5% more rate, the increase in S.I for 10 years = Rs.600  (given)

So, at 5% more rate, the increase in SI for 1 year = 600/10 = Rs.60/-

i.e. Rs.60 is 5% of the invested sum

So, 1% of the invested sum = 60/5

Therefore, the invested sum = 60 × 100/5 = Rs.1200

                                         A                  B                   C

investment                    3x                 4x                  5x

Rate of return              6y%              5y%                4y%

Return                        18xy100 20xy100 20xy100                

               Total = (18+20+20) = 58xy100

     B's earnings - A's earnings  = 2xy100 = 250

     Total earning = 58xy100 = 7250

On carefully inspecting this question, one can understand that there are two days which are important and these are:

A. My Birthday.

B. The day when I am making this statement.

If you think for a while, you will understand that such statements can be made only around the year’s end. So, if my birthday is on 31 December, then I will be making this statement on 1 January.

I will further explain using the following example:

1. Consider that today is 01 January 2017.

2. Then, the day before yesterday was 30 December 2016 and according to the question I was 25 then.

3. Yesterday was 31 December 2016, which happens to be my birthday too (Woohoo!), and my age increases by one to become 26.

4. I will turn 27 on my birthday this year (31 December 2017).

5. I will turn 28 on my birthday next year (31 December 2018).

Now, if you read the question again, it will make more sense:

The day before yesterday(30 December 2016), I was 25 years old and next year(31 December 2018) I will be 28.

2500 in 5th year and 3000 in 7th year
So in between 2 years Rs. 500 is increased => for a year 500/2 = 250
So, per year it is increasing Rs.250 then in 5 years => 250 x 5 = 1250
Hence, the initial amount must be 2500 - 1250 = Rs. 1250