Answer:Part 4) The number of meters by which each dimension must be increased is [tex]2\ m[/tex]Part 5) The ball hit the ground at [tex]t=9\ sec[/tex]Step-by-step explanation:Part 4) we know thatThe area of the original Joe's garden is equal to[tex]A=6*4=24\ m^{2}[/tex]Increasing the length and the width with the same amount to double the areawe haveLetx------> the number of meters by which each dimension must be increased[tex]24*2=(x+6)(x+4)\\48=x^{2}+4x+6x+24\\x^{2}+10x-24=0[/tex]Using a graphing tool solve the quadratic equationsee the attached figureThe solution is [tex]x=2\ m[/tex]Part 5) we have[tex]h=-144t-16t^{2}[/tex]we know thatTo calculate after how many seconds will the ball hit the ground, find the t-intercept of the functionRemember thatThe t-intercept of the function h(t) is the value of t when the value of h(t) is equal to zerosoequate h(t) to zero[tex]-144t-16t^{2}=0[/tex]Using a graphing toolFind the t-interceptsee the attached figureThe solution is [tex]t=9\ sec[/tex]