Step-by-step explanation:
10 minutes = 600 seconds
Seconds per question is seconds/questions
Divide 600 by the number of questions:
600/(number of questions) = ________ seconds per question
Any odd number can be expressed by 2n+1.
For example,
2n+1=111
2n=110
n=110/2=55
means that 111 is 2n+1 for n=55
Thus if an odd number is 2a+1, the next few numbers are as follows:
2a+1, 2a+2, 2a+3, 2a+4, 2a+5
So 2a+1, 2a+3 and 2a+5 are 3 consecutive odd numbers.
Back to our problem:
three consecutive odd numbers whose sum is 63 are:
(2n+1)+(2n+3)+(2n+5)=63
6n+9=63
6n=63-9=54
n=54/6=9
2n+1=2*9+1=18+1=19, the 2 next odd numbers are 21 and 23
Answer: 19, 21, 23
Answer: 20
Step-by-step explanation:
x+y=5
x-y=4
---------
x+y=5
x=4+y
--------
(4+y)+y=5
4+y+y=5
4+2y=5
2y=1
y=0.5
x=4.5
---------
x²-y²=(4.5)²-(0.5)²=20.25-0.25=20
