The number of 4 letter words (with or without meaning) that can be formed from the eleven letters of the word 'EXAMINATION' is _______.

$$\mathop {\lim }\limits_{x \to 0} {{\int_0^x {t\sin \left( {10t} \right)dt} } \over x}$$ is equal to

If $$A = \left( {\matrix{ 2 & 2 \cr 9 & 4 \cr } } \right)$$ and $$I = \left( {\matrix{ 1 & 0 \cr 0 & 1 \cr } } \right)$$ then 10A^–1 is equal to :

The mean and variance of 20 observations are found to be 10 and 4, respectively. On rechecking, it was found that an observation 9 was incorrect and the correct observation was 11. Then the correct variance is