Which of the following graphs is isomorphic to

Consider the function $$f\left( x \right) = \sin \left( x \right)$$ in the interval $$x \in \left[ {\pi /4,\,\,7\pi /4} \right].$$ The number and location(s) of the local minima of this function are

What is the correct translation of the following statement into mathematical logic? "Some real numbers are rational"

Consider the virtual page reference string $$$1,2,3,2,4,1,3,2,4,1$$$
On a demand paged virtual memory system running on a computer system that has main memory size of $$3$$ page frames which are initially empty. Let $$LRU,$$ $$FIFO$$ and $$OPTIMAL$$ denote the number of page faults under the corresponding page replacement policy. Then