Average

Let the present age of X and Y be 5a, 4a
If they got married t years ago,
(5a - t)/(4a - t) = 6/4
(5a - t)/(4a - t) = 3/2 ----------------eqn (1)
After 4 years from now, their age ratio becomes
(5a + 4)/(4a + 4) = 9/8 ---------------- eqn (2)
Now from equation 1 and 2, equation 2 can be solved easily.
Taking equation 2 to find a,
(5a + 4)/(4a + 4) = 9/8
8(5a + 4) = 9(4a + 4)
40a + 32 = 36a + 36
4a = 4
a = 1.
Now substitute the value of a in equation 1, we get
(5(1) - t)/(4(1) - t) = 3/2
(5 - t)/(4 - t) = 3/2
2(5 - t) = 3(4 - t)
10 - 2t = 12 - 3t
t = 2 years.
Hence, X & Y got married 2 years ago.

The average age of a group of 10 students is 24.
∴ the sum of the ages of all 10 of them = 10 × 24 = 240
When two students joins the group, the average increase by 1. New Average = 25
Now there are 12 students
∴ sum of all the ages of 12 students = ( 12 X 25 ) = 300
∴ the sum of the ages of two students who joined = 300 - 240 = 60
And the average age of these two students = 30

⇒ The smallest cube divisible by 16 is 64.
⇒ Lets assume the average salary before the manager's salary is included is x
⇒ After addition of Manager's salary the average increases by 100
⇒ We can write down the above information in form of an equation as:
⇒ 64x + 9500 = 65 × (x + 100)
⇒ Solving for x, we get×= 3000
⇒ The final average is 3000 + 100 = ₹ 3100
⇒ Hence, option D is correct.

⇒ Total weight of Amar, Visera and Chandan = 70 × 3 = 210 kg
⇒ Again, Amar + Visera + Chandan + Vishal = 66 × 4 = 264 kg ......... (i)
⇒ Weight of Vishal = 264 - 210 = 54 kg
⇒ Weight of Tahir = 54 + 6 = 60 kg
⇒ Now, as per the question
⇒ Visera + Chandan + Vishal + Tahir = 75 × 4 = 300 kg. ................... (ii)
⇒ Subtracting (i) from (ii), we get
⇒ Tahir - Amar = 60 - Amar = 300 - 264 = 36
⇒ ∴ weight of Amar = 60 - 36 = 24 kg
⇒ Hence, option D is correct.

Details

Details

Let find the Temperature of Thursday:
⇒ Temperature of Monday, Tuesday and Wednesday = 30×3 = 90.
⇒ Temperature of Tuesday, Wednesday and Thursday 33×3 =99.
⇒ Thursday - Monday = 9
⇒ Thursday - 32 = 9
⇒ Thursday temperature = 32+9 = 41
Hence the answer is : 41 °

Total weight = Average weight × No of persons

Total weight of X, Y and W = 50 × 3 = 150 kg
Again, X + Y + W + Z = 66 × 4 = 264 kg ......... (i)
Weight of Z = 264 - 150= 114 kg
Weight of U = 114 + 6 = 120 kg
Now, as per the question
Y + W + Z + U = 75 × 4 = 300 kg. ................... (ii)
Subtracting (i) from (ii), we get
U - X = 120 - X = 300 - 264 = 36
∴ weight of X = 120 - 36 = 84 kg
Hence, The weight of X is 84 kg

Details

Given:
The average revenues of 9 consecutive years of a organisation = ₹ 80 lakhs
Average of first 5 years = ₹ 75 lakhs
Average of last 5 years = ₹ 87 lakhs
∴ Revenue of 5th yr = Revenue of first 5 years + Revenue of last 5 years - Revenue of first 9 years
= (5×75) + (5×87) - (9×80)
= 90 lakhs.