Average Test-5 (Calculating weighted average)

Answer: Option B

Explanation

Sum of the total height of 13 girls in the class =$13\times \frac{1880}{13}$

= 1880 cm

Sum of the total height of 11 boys in the class =$11\times \frac{1864}{11}$

= 1864 cm

∴ Overall average height =$\frac{1880+1864}{24}$=156 cm

Hence, Option B is correct.

Answer: Option B

Explanation

Given,

Total score of Rahul, Manish and Suresh =3×63=189

Ajay's score =63+30=93

Rahul's score =78

Manish's score= 68

So, sum of Manish's and suresh's score = 68+43=111

Hence, Option B is correct.

Answer: Option A

Explanation

Let the required average age of the remaining boys be 'x'

Now, according to the question

80×15=15×16+25×14+40×x

⇒ 1200=240+350+40x

⇒ 40x=1200-240-350

⇒ 40x=610

⇒x=$\frac{610}{40}$=15.25 yr

Hence, Option A is correct.

Answer: Option D

Explanation

Given,

Total sum of five numbers = 56×5=280

Sum of first four numbers = 4×54

= 216

∴ Value of fifth number =280-216

   =64

Hence, Option D is correct.

Answer: Option B

Explanation

given,

Total sum of five numbers =5×65=325

Sum of first two numbers =2×81=162

Sum of last two numbers =2×38

      =76

So, third number =325-(162+76)

  =325-(238)

  =87

Hence, Option B is correct.