The probability for the ECE board examinees from a certain school to pass the subject Mathematics is $3 / 7$ and for the subject Communications is $5 / 7$ . If none of the examinees fails both subject and there are $4$ examinees who pass both subjects, find the number of examinees from that school who took the examinations.

20

No worries! We‘ve got your back. Try BYJU‘S free classes today!

25

No worries! We‘ve got your back. Try BYJU‘S free classes today!

30

No worries! We‘ve got your back. Try BYJU‘S free classes today!

28

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

Open in App

Solution

The correct option is D $28$
Let the number of examinees be $x$ .
The number of examinees passed in mathematics is $\frac{3 x}{7}$ .
The number of examinees passed in Communications is $\frac{5 x}{7}$ .
The number of examinees passed in mathematics and communications is $4$ .
$\Rightarrow x = \frac{5 x}{7} + \frac{3 x}{7} - 4$
$\Rightarrow x = 28$

Suggest Corrections

Similar questions

Q. In an examination,

42 %

students failed in mathematics and

52 %

failed in science. If

17 %

failed in both the subjects, find the percentage of those who passed in both the subjects.

Q. In a certain examination 77 p.c. pass in English and 34 p.c. fail in Mathematics. If 13 p.c. fail in both subjects and 784 passes in both the subjects. Find the total number of candidates.

___

Q. In a competitive exam 50 students passed in English. 60 students passed in Mathematics. 40 students passed in both the subjects. None of them fail in both the subjects. Find the number of students who passed at least in one of the subjects ?

In a combined test in Maths and Science 8% failed in both subjects and 12% passed in both subjects. If the total number of students who gave the exam is 500, then number of students who passed in both subjects is ___ and the number of students who failed in both subjects is ___

Q. In a science talent examination, 50% of the candidates fail in Mathematics and 50% fail in Physics. If 20% fail in both these subjects, then the percentage who pass in both Mathematics and Physics is:

Join BYJU'S Learning Program

The correct option is D 28Let the number of examinees be x.The number of examinees passed in mathematics is 3x7.The number of examinees passed in Communications is 5x7.The number of examinees passed in mathematics and communications is 4.⇒x=5x7+3x7−4⇒x=28