@Magma, The solution provided by them should be wrong...
Note that given Process Size = 232. and Page Size = 1 Kb = 210 b = 27 Bytes
no.of pages in the process ( no.of entries in PT1 ) = $\frac{2^{32}}{2^{7}}$ = ${2^{25}}$
===> Size of 1st level Page Table = ${2^{25}}$ * 22 B = ${2^{27}}\;B$
no.of pages in the PT1 ( no.of entries in PT2 )= $\frac{2^{27}}{2^{7}}$ = ${2^{20}}$
===> Size of 2nd level Page Table = ${2^{25}}$ * 22 B = ${2^{22}}\;B$
no.of pages in the PT2 ( no.of entries in PT3 ) = $\frac{2^{22}}{2^{7}}$ = ${2^{15}}$
===> Size of 3rd level Page Table = ${2^{25}}$ * 22 B = ${2^{17}}\;B$
no.of pages in the PT3 ( no.of entries in PT4 ) = $\frac{2^{17}}{2^{7}}$ = ${2^{10}}$
===> Size of 4th level Page Table = ${2^{10}}$ * 22 B = ${2^{12}}\;B$
no.of pages in the PT4 ( no.of entries in PT5 ) = $\frac{2^{12}}{2^{7}}$ = ${2^{5}}$
===> Size of 5th level Page Table = ${2^{5}}$ * 22 B = ${2^{7}}\;B$ ===> Fit in 1 Page
Over Head By page tables = $ ({2^{27}} + {2^{22}} + {2^{17}} + {2^{12}} + {2^{7}} ) \;B$