Question

Zara wakes up late on average $3$ days in every $5$.
If zara wakes up late, the probability he is late for school $=\frac{9}{10}$
If zara doesn't wake up late, the probability he is late for school $=\frac{9}{10}$
Using Tree diagram find what percent of days does Zaraget to school on time?

• A. $34$%
• B. $66$%
• C. $67$%
• D. None of these

Answer 1

Answer: (D)

None of these

The probability that zara wakes up late is $\frac{3}{5}$.

The probability that zara doesnt wakes up late is $c\frac{2}{5}$.

If zara wakes up late , then the probability that he is on time to school is $1-\frac{9}{10}=\frac{1}{10}$.

If zara doesnt wakes up late , then the probability that he is on time to school is $1-\frac{9}{10}=\frac{1}{10}$.

The probability that zara is on time to school is $\frac{1}{10}\times \frac{3}{5}+\frac{1}{10}\times \frac{2}{5}=\frac{1}{10}$.

The percentage is $10$%.