Exams

C.I. =Rs[4000x(1+10/100)²-4000]

Rs.(4000x11/10x11/10-4000) = Rs.940.

Sum

=Rs. [420 *100 /3 * 8]

= Rs.1750.

Let the Cost price of the powerbank = Rs. P

But given that by selling it at Rs. 1950, it gives a loss of 25%

=> P x 75100 = 1950
=>P = 1950 x 10075 = Rs. 2600
Now, to get a profit of 25%

Selling Price = 2600 x 125100 = Rs. 3250.

Unit digit of this expression is always 1 as the base ends with 1. 

For the tenth place digit we need to multiply the digit in the tenth place of the base and unit digit of the power and take its unit digit.

i.e, tenth place digit in 2151 is 5 and

tenth place digit in power 415 is 1

And the units digit in the product of 5 x 1 = 5

Therefore, last two digits of 2151415 is 51.

75% of 450 + ? % of 560 = 600 

$$\begin{gathered} 75 x 450100 + ? x 560100 = 600 \\ 75 x 92 + 28p5 = 600 \\ 75x9x5 + 56p10 = 600 \\ 3375 + 56p = 6000 \\ 56p = 2625 \\ p = 46.875 \end{gathered}$$

Hence, in the given question ? = 46.875

The students should sit in between two teachers. There are 7 gaps in between teachers when they sit in a roundtable. This can be done in 7P6ways. 7 teachers can sit in (7-1)! ways.

 Required no.of ways is = 7P6.6! = 7!.6!