Percentage Questions

Let total number of votes enrolled = x
No. of voted cast = 70% of x = 0.7x
Valid votes = 98% of 0.7x
⇒ 60% of total valid votes = 7203 = 60% of 98% of 0.7x
⇒ 0.6 X 0.98 X 0.7x = 7203
⇒ x = 7203 / (0.6 X 0.98 X 0.7)
⇒ x = 17500

n (A) = (60/100 * 96) = 288/5, n (B) = (30/100 * 96) = 144/5, n (A ∩ B) = (15/100 * 96) = 72/5.

n(A ∪ B) = n (A) + n (B) - n (A ∩ B) = 72.

So, people who had either or both types of lunch = 72.

Hence, people who had neither type of lunch = (96 - 72)= 24.

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

20 x 55 x 66 = L x 65 x 70
Here L = 72,600/4550 = 15.95 =~ 16
Reduction is 20-16 = 4

which is 20% reduction.

This can be solved as

$$\begin{gathered} 20 1 - 4202 = 20 1 - 152 \\ = 20452 \\ = 20 1625 \\ = 645 \\ = 12.8 \end{gathered}$$

74.99% of 1299 + 8.98% of 1899 = ? 

$$\begin{gathered} ? = 75 x 1400100 + 9 x 1800100 \\ ? = 1050 + 162 \\ ? = 1212. \end{gathered}$$

Let the rquired number be 'P'

According to the question,

$$\begin{gathered} 100 x P100 = 20 \\ => P = 20 x 100100 = 20 \end{gathered}$$

Hence, 100 percent of the number 20 is 20.

Now, you can also try for

20 percent of what number is 100

$$\begin{gathered} 20 x P100 = 100 \\ => P = 100 x 10020 = 500 \\ => P = 500 \end{gathered}$$

Hence, 20 percent of the number 500 is 100.

Let the total applicants be 100

Then, 20% got 85 marks

i.e 20 x 85 = 1700

and 25% got 95 marks

 i.e 25 x 95 = 2375

Now, the remaining applicants are 55 and let the average marks scored by them be x.

Therefore, 2375 + 1700 + 55x  =  60×100 

6000 - 4075 = 55x

55x=1925

x=35.