Average Test-5 (Calculating weighted average)

Answer: Option A

Explanation

Given,

Total present ages of A and B = 18×2+6= 42 yr

Now, Total ages of A,B and C=3×22

   =66 yr

C's age =66-42

   = 24 yr

Hence, Option A is correct.

Answer: Option B

Explanation

Given,

Monday to wednesday M+T+W=3×37

      =111°C   ___(1)

Tuesday to thursday T+W+TH=3×34

    =102°C    ____(2)

On subracting Eq(2) from Eq(1), we get

M-TH=(111-102)

= 9°C

Now, $\frac{\mathrm{Th}}{4}$=9°C

∴ Th=9×4=36°C

Hence, Option B is correct.

Answer: Option D

Explanation

Average weight of 3 boys P, T and R =54$\frac{1}{3}$kg

∴ Total weight of P, T and R =3×$\frac{163}{3}$

 =163 kg

Again, total weight of T, F and G=3×53

= 159 kg

Further it can be solved, so data is inadequate.

Hence, Option D is correct.

Answer: Option E

Explanation

Let three numbers be x,y and z.

According to the question,

$=\frac{x+y}{2}-\frac{y+z}{2}=15$

= x+y-y-z=30

= x-z=30

Hence, Option E is correct.

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.