void page4() {
  String t = "Step 4 - The p-value";
  textFont(myboldfont, 18);
  text(t, 30, 170);
  textFont(myfont, 18);

  t = "Use Table A.3 in the back of the book to the find the area to the left of z* under N(0,1)";
  t += " following the corresponding row and column (with at least 3 decimal places). Type in the following textbox(s) then click Answer:";
  drawStrings(t, 30, 200, 25);

  float rowl, coll, rowu, colu;

  if (testl > 3.69) {
    rowl = 3.6;
    coll = 0.09;
  }
  else if (testl < -3.69) {
    rowl = -3.6;
    coll = 0.09;
  }
  else { 
    //rowl = int(testl * 10.0) / 10.0;
    //coll = round(abs(testl-rowl) * 100.0) / 100.0;
    rowl = float(round(testl*100.0)/10)/10.0;
    coll = abs(float(round(testl*100.0)%10)/100.0);
  }

  if (testu > 3.69) {
    rowu = 3.6;
    colu = 0.09;
  }
  else if (testu < -3.69) {
    rowu = -3.6;
    colu = 0.09;
  }
  else { 
    // rowu = int(testu * 10.0) / 10.0;
    // colu = round(abs(testu-rowu) * 100.0) / 100.0;
    rowu = float(round(testu*100.0)/10)/10.0;
    colu = abs(float(round(testu*100.0)%10)/100.0);
  }

  if (rowu<0) {
    pu = (float)(Probability.normcdf(rowu-colu));
  }
  else {
    pu = (float)(Probability.normcdf(rowu+colu));
  }

  if (rowl<0) {
    pl = (float)(Probability.normcdf(rowl-coll));
  }
  else {
    pl = (float)(Probability.normcdf(rowl+coll));
  }

  if (aStudy.k==0) {
    text(nf(coll, 1, 2), 230, 280);
    text(nf(rowl, 1, 2), 100, 345);

    image(smalldown, 230, 290);
    image(smallright, 150, 320);

    text("Z_l", 170, 300);
    tf3.setVisible(false);
  }
  else if (aStudy.k==1) {
    text(nf(colu, 1, 2), 230, 280);
    text(nf(rowu, 1, 2), 100, 345);

    image(smalldown, 230, 290);
    image(smallright, 150, 320);

    text("Z_u", 170, 300);
    tf3.setVisible(false);
  }
  else {
    text(nf(coll, 1, 2), 230, 280);
    text(nf(rowl, 1, 2), 100, 345);

    image(smalldown, 230, 290);
    image(smallright, 150, 320);

    text("Z_l", 170, 300);

    text(nf(colu, 1, 2), 500, 280);
    text(nf(rowu, 1, 2), 370, 345);

    image(smalldown, 500, 290);
    image(smallright, 420, 320);

    text("Z_u", 440, 300);
    tf3.setVisible(true);
  }

  fill(0, 0, 255);
  drawStrings(feedback, 80, 380, 25);
  tf2.setXY(200, 330);
  tf3.setXY(470, 330);
}