Question

After playing 500 games, Sachin's success rate at Spider Solitaire is 49%. Sachin detemines that now on he will win every game. How many extra games he has to win so that his success rate increases to 50%.
Options:
A. 1
B. 5
C. 10
D. 20
Step by step explanation pls.

Answer 1

Answer:

C. Sachin has to win 10 extra games.

Step-by-step explanation:

Sachin played 500 games

His success rate is 49%

Therefore, he won $=\frac{49}{100} of 500$ = 49x5 = 245 games

He targets to increase his success rate to 50%.  

Let's assume that, in order to achieve that, he need to play additional x games, winning all of those.

Therefore, He will end up winning $=\frac{50}{100} of (500+x)$ $=\frac{500+x}{2}$ games

Therefore, $\frac{500+x}{2} - 245 = x$

$=> 500+x - 490 = 2x$  [multiplying both sides by 2]

∴ $x = 10$