$.$ Consider a relation s$($A$,$B$)$ with the following characteristics:

$$ s has $700,000$ tuples with $70$ tuples per disk block

$$ s has an index on attribute A with index height x$=2($i$.$e$.,$ the index has nodes on $3$ levels$)$

$$ The values that the attribute A takes in relation s are integers which are uniformly distributed in the range $1...200.$

$[$Uniformly distributed $$ there are roughly $3500$ tuples for each A value.$]$

$(1.$a$)$ Assuming that the index on A is a secondary index, estimate the number of disk block accesses needed to

compute the query $\backslash$sigma A$=18($s$).$

$(1.$b$)$ What would be the estimated cost if the index were a clustering index?