Since every child is equally likely to be born, the probability of getting 2 girls and 2 boys is (1/2)^4 = 1/16.

Now the 2 girls and the two boys can be arranged in 4! ways. However G1G2B1B2 is the same as G2G1B1B2 and many other such combinations. So 4!/4(1/16) = 3/8.

Are you sure that OA is E?

Altitude or median

Hi,

Will the median or altitude divide a triangle in to 2 congruent triangles?
Or median always divide triangles in to 2 equal halves whereas altitude does it only in case of right triangles inscribed in a circle?

consecutive integers

Let a be the sum of x consecutive positive integers. Let b be the sum of y consecutive positive
integers. For which of the following values of x and y is it NOT possible that a = b?
(A) x = 2; y = 6
(B) x = 3; y = 6
(C) x = 6; y = 4
(D) x = 6; y = 7
(E) x = 7; y = 5

Can we not assume the mortality rate for the year of 1970 as m, hence for 1972 it would be 0.92*0.92m and for 1976 0.92^6 m . So that wouldn't that be sufficient to calculate the percent decrease.

Even after we figure out that z>0, to find the if m is also > 0, we may substitute the value of z is each of the 2 equations - 1) m-3z > 0 Since m> 3z, m is greater than 0. Hence m+z>0. (2) 4z-m > 0 4z>m. Say z=1, m<4, so if m is negative say -10 , m+z < 0 Say m=3 , m<4, so m+z>0. Hence shouldnt the...

Q-The sum of the even numbers between 1 and n is 79*80, where n is an odd number, then n=? The answer i have is 79 whereas i m gettin 159... The problem becomes less tricky if you realize that 79*80 represents the formula for determining the sum of evenly spaced integers: Sum = (number of integers)...

Experts please comment.
Even I chose B, but the OA is C .

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