PLEASE HELP ME PLEASE 10 POINTS ON IT PLEASE

6. He had Rs728.

7. There are 1875 pupils in the school.

Step-by-step explanation:

6.

He started with x amount of money.

He spent 1/4 of x. x - (1/4)x = (4/4)x - (1/4)x = (3/4)x

After buying the lottery tickets, he had (3/4)x left.

Then he spent 2/7 of the remainder on scratch cards.

He spent 2/7 of (3/4)x on scratch cards. Since he spent

2/7 of the reminder on scratch cards, he has 5/7 of the reminder left.

5/7 * (3/4)x = (15/28)x

He has (15/28)x left. He has Rs390 left.

(15/28)x = 390

15x = 390 * 28

15x = 10920

x = 728

He had Rs728.

7.

8/15 of the pupils are girls.

1 - 8/15 = 15/15 - 8/15 = 7/15

7/15 of the pupils are boys.

Let x = total number of pupils in the school

(8/15)x = (7/15)x + 125

Multiply both sides by 15.

8x = 7x + 1875

x = 1875

There are 1875 pupils in the school.

6. Rs728.

7.  1875

the answer   is 200

step-by-step explanation:

this is a problem about poisson probabilities.   i don't know if you've

already studied poisson distributions, or if you have a place to look

to read more about the subject.  

here's how you can see a poisson distribution coming.   when there are

a lot of events that may happen at any time (or any place), and when

you're counting how many of them happen at a particular time (or a

particular place), and each event is independent of the others, then

the result is a poisson distribution.   this is roughly true for the

chocolate chips; one chip being in a cookie has only a small effect on

the probability that another chip will be in the cookie.

once you know you have a poisson distribution, you know a lot.   there

is only one parameter to a poisson distribution, so if you know the

mean, you know everything.   the form of the distribution is

  probability of n chips = {[e^(-x)]*(x^n)} / (n! )