averages Model Questions & Answers, Practice Test for ssc cgl tier 1 2023

Answer: (d)

Increase in weight

= 65 – 45 = 20 kg.

∴ Increase in average

= $20/53 = 0.38$

∴ Actual average weight

= 58 – 0.38 = 57.62

Answer: (b)

Let the total journey be x km.

Then $x/3$ km at the speed of 25 km/hr and $x/4$ km at 30 km/hr and the rest distance $(x - x/3 - x/4) = 5/12x$ at the speed of 50 km/hr.

Total time taken during the journey of x km

= $x/{3 × 25} hrs + x/{4 × 30} hrs + {5x}/{12 × 50}hrs$

= ${18x}/600 hrs = {3x}/100 $ hrs

∴ average speed = $x/{{18x}/600} = 100/3 = 33{1}/3$ km/hr

Answer: (b)

Let the present age be x yrs. Then

125% of (x – 10) = x; and 83$1/3$% 3 of (x + 10) = x

∴ 125% of (x – 10) = 83$1/3$% 3 of (x + 10)

$5/4(x = 10) = 5/6(x + 10)$

or, $5/4x - 5/6x = 50/6 + 50/4$

or, ${5x}/12 = 250/12$

∴ x = 50 yrs.

Answer: (c)

Since it is obvious that just after the birth of the youngest member (i.e., child) was 6 family members in the family.

Therefore at the time of the birth of the youngest child the elder child's age was 6 years.

Now the sum of their ages

= x + (x + 6) = 12 = (168 – 156)

⇒ x = 3

Answer: (b)

Recognise that the journey by bus and that by cycle are of equal distance.

Hence, we can use the short cut illustrated earlier to solve this part of the problem.

Using the process explained above, we get average speed of the second half of the journey as

10 + 1 × 5 = 15 kmph

Then we employ the same technique for the first part and get 15 + 1 × 9 = 24 kmph