Let m and n (m < n) be the roots of the equation x2 – 16x + 39 = 0. If four terms p, q, r and s are inserted between m and n to form an AP, then what is the value of p + q + r + s ?
29
30
32
35
A geometric progression (GP) consists of 200 terms. If the sum of odd terms of the GP is m, and the sum of even terms of the GP is n, then what is its common ratio ?
m/n
n/m
m + (n/m)
n + (m/n)
If the roots of the equation
a(b - c)x2 + b (c – a)x + c(a - b) = 0
are equal, then which one of the following is correct ?
a, b and c are in AP
a, b and c are in GP
a, b and c are in HP
a, b and c do not follow any regular pattern
Arithmetic meanof 10 observation is 60 and sum of squares of deviations from 50 is 5000. What is the standard deviation of the observation ?
20
21
22, 36
24, 70
A.
20
The expected value of the observations is 60.
E(X) = 60
The sum of squared deviations from 50 is 10 times the expected squared deviations from 50. Divide by 10 on both sides and substitute 60 for the expected value. The expected squared value of the observations can then be solved tobe 4000.
E(X2) – 100E(X) + 2500 = 500
The standard deviation of the 10 observed values, 20, is equal to the square root of the difference between the expected squared value of the observations and the squared expected value of the observations.
Hence, option A is correct
If (1 + 2x – x2)6 = a0 + a1x + a2x2 + ... + a12x12, then what is a0 – a1 + a2 – a3 + a4 - ... + a12 equal to ?
32
64
2048
4096