Assume that for a certain processor, a read request takes $$50$$ nanoseconds on a cache miss and $$5$$ nanoseconds on a cache hit. Suppose while running a program, it was observed that $$80\% $$ of the processor's read requests result in a cache hit. The average read access time in nanoseconds is __________.

Which one of the following hash functions on integers will distribute keys most uniformly over $$10$$ buckets numbered $$0$$ to $$9$$ for $$𝑖$$ ranging from $$0$$ to $$2020$$?

Consider a complete binary tree where the left and the right sub-trees of the root are max-heaps. The lower bound for the number of operations to convert the tree to a heap is

A binary tree $$T$$ has $$20$$ leaves. The number of nodes in $$T$$ having two children is _______________.