Answer:
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
Answer: 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
Answer: There are 1875 pupils in the school.
Answer:
B
Step-by-step explanation:
Sine is opposite/hypotenuse. Sine C would be 5/13 so option B is correct.
I think it’s C because the base is 180 degrees so C would be the best response
Answer:
111.2 units³
Step-by-step explanation:
Base area = 2(a² + ½ab)
2(4)² + (4)(5.9)
= 55.6 units²
Volume = Base area × c
55.6 × 2
= 111.2 units³
Given :
The half-life of carbon 14 is 5,730 years.
To Find :
How much would be left of an original 50-
gram sample after 2, 292 years.
Solution :
We know, rate law for first order reaction is given by :
...1)
Here,
is initial amount and
is final amount.
And ![k = \dfrac{ln\ 2}{t_{0.5}}](https://tex.z-dn.net/?f=k%20%3D%20%5Cdfrac%7Bln%5C%202%7D%7Bt_%7B0.5%7D%7D)
Putting value of half time in above equation, we get :
![k = \dfrac{ln\ 2}{5730}\\\\k = 1.21\times10^{-4} \ /s](https://tex.z-dn.net/?f=k%20%3D%20%5Cdfrac%7Bln%5C%202%7D%7B5730%7D%5C%5C%5C%5Ck%20%3D%201.21%5Ctimes10%5E%7B-4%7D%20%5C%20%2Fs)
Putting value of k in equation 1) , we get :
![[A] = 50\times e^{-1.21\times 10^{-4}\times 2292} = 37.89\ gm\\\\](https://tex.z-dn.net/?f=%5BA%5D%20%3D%2050%5Ctimes%20e%5E%7B-1.21%5Ctimes%2010%5E%7B-4%7D%5Ctimes%202292%7D%20%3D%2037.89%5C%20%20gm%5C%5C%5C%5C)
Hence, this is the required solution.