Average Test-7 (Complete Revision)

Answer: Option A

Explanation

Given,

Total marks obtained by 120 students = 120×35

 = 4200

Let the number of passed candidates = x

Then, total marks obtained by passed candidates = x×39

And, total marks obtained by failed candidates =(120-x)×15

Again, 39x+(120-x)×15=4200

⇒ 39x+1800-15x=4200

⇒ 24x=2400

∴ x=$\frac{2400}{24}=100$

Hence, Option A is correct.

Answer: Option A

Explanation

According to the question

Total correct weight = 40×60-36+33

= 2400 - 3

= 2397 kg

The actual average weight of the students in the class

$= \frac{2397}{60}$

= 39.95 kg

Hence, Option A is correct.

Answer: Option A

Explanation

Here we can use the formula

$$\begin{gathered} \text{Average (A)=}\frac{\mathrm{Sum} \mathrm{of} \mathrm{observations} \left(\mathrm{S}\right)}{\mathrm{No}. \mathrm{of} \mathrm{observations} \left(\mathrm{N}\right)} \\ \text{⇒ S=A×N} \end{gathered}$$

According to the question,

Sum of weight of 21 boys (A=64, N=21)

⇒S=64 X 21 =1344

Later, Wieght of the teacher is added, the average increases by 1 kg. (so A=65, N=22)

So, sum of 21 boys and teacher weight is

⇒S=65 X 22 =1430

Now,

The teacher's weight =(sum of weight of 21 boys)-(Sum of 21 boys and teacher weight)

 = 1430-1344

 = 86 kg.

Hence, Option A is correct.

Answer: Option C

Explanation

According to the formula,

The average of 1st 'n' natural numbers= $\frac{\mathrm{n}+1}{2}$

∴ Average of 1st 91 natural numbers

$$\begin{gathered} = \frac{91+1}{2} \\ =\frac{92}{2} \\ =46 \end{gathered}$$

Hence, Option C is correct.

Answer: Option C

Explanation

Given set of scores= 566, 455, 678, 989, 342, 715

We know the formula,

 $\mathrm{Average} \left(\mathrm{A}\right)=\frac{\mathrm{Sum} \mathrm{of} \mathrm{given} \mathrm{values} \left(\mathrm{S}\right)}{\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{values} \left(\mathrm{N}\right)}$

 Here,

 Sum of given values(S)

= 566+455+678+989+342+715

= 3745

Total number of values(N)= 6

Substituting these values we get (A),

 $= \frac{3745}{6}=624.16$

Hence, Option C is correct.