John’s grade was in the 80th percentile out of 70 grades in her class. In another class of 50 students there were 20 grades higher than John’s. If nobody had John’s grade, then John was what percentile of the two classes combined? Pick.
A) 80
B) 75
C) 72
D) 65
E) 60
Being in 80% percentile out of 70 grades means John was 57th (from the least grade) in the class (as long as nobody had John 's grades), he outscored 56.   In another class his grade would rank him 31 (from the least grade out of 51, 50+ John), 31 had the grades lower than John.   So in combined classes he outscored 56+30= 
<gadget id="calculator">56+30</gadget>
<output>86</output>
86. There are 120 students 86/120=0.717 =0.72 after rounding.   Answer: C(72%)   Generally being in x% means that x% has the grades less than you.   John in 80% --&gt; he outscored 80% of of 70=56 (Amy is 57th).   Of the 50 grades from another class, 20 were higher than John 's, and the rest were lower --&gt; rest is 30, hence John outscored 30.   So out of total 70+50=180, John outscored  56+30= 
<gadget id="calculator"> 56+30</gadget>
<output>86</output>
86. Hence he is in 86/120=72%.   72   Answer: 72
<result>C</result>
John’s grade was in the 80th percentile out of 70 grades in her class. In another class of 50 students there were 20 grades higher than John’s. If nobody had John’s grade, then John was what percentile of the two classes combined?