Interview question based on skill :
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Total Questions: 20
1. .What will be the output of following code ? > g <- function(x) { + a <- 3 + x+a+y + ## 'y' is a free variable + } > g(2)
Correct Answer is : Error
2. ________ functions can be “built which contain all of the necessary data for evaluating the function
Correct Answer is : Objective
3. Which of the following language supports lexical scoping ?
Correct Answer is : All of the mentioned
4. _________ require you to pass a function whose argument is a vector of parameters.
Correct Answer is : opt()
5. Point out the correct statement :
Correct Answer is : An environment is a collection of (symbol, value) pairs, i.e. x is a symbol and 3.14 might be its value
6. What will be the output of the following code ? function(p) { params[!fixed] <- p mu <- params[1] sigma <- params[2] ## Calculate the Normal density a <- -0.5*length(data)*log(2*pi*sigma^2) b <- -0.5*sum((data-mu)^2) / (sigma^2) -(a + b) } > ls(environment(nLL))
Correct Answer is : “data” “fixed” “params”
7. What will be the output of the following code ? > nLL <- make.NegLogLik(normals, c(FALSE, 2)) > optimize(nLL, c(-1, 3))$minimum
Correct Answer is : empty
8. What will be the output of the following code ? > nLL <- make.NegLogLik(normals, c(1, FALSE)) > optimize(nLL, c(1e-6, 10))$minimum
Correct Answer is : 1.800596
9. The _________ function is used to plot negative likelihood.
Correct Answer is : plot()
10. What will be the output of following code ? > g <- function(x) { + a <- 3 + x+a+y + ## 'y' is a free variable + } > y <- 3 > g(2)
Correct Answer is : 8
11. ________ generate random Normal variates with a given mean and standard deviation
Correct Answer is : rnorm
12. Point out the correct statement :
Correct Answer is : R comes with a set of pseudo-random number generators
13. ______ evaluate the cumulative distribution function for a Normal distribution
Correct Answer is : pnorm
14. _______ generate random Poisson variates with a given rate
Correct Answer is : rpois
15. Point out the wrong statement :
Correct Answer is : For each probability distribution there are typically three functions
16. Which of the following evaluate the Normal probability density (with a given mean/SD) at a point ?
Correct Answer is : dnorm
17. _________ is the most common probability distribution to work with.
Correct Answer is : Gaussian
18. What will be the output of the following code ? > pnorm(2)
Correct Answer is : 0.9772499
19. _________ ensures reproducibility of the sequence of random numbers.
Correct Answer is : set.seed()
20. Point out the correct statement :
Correct Answer is : You should always set the random number seed when conducting a simulation
