31
The next number in the sequence 5-7-13-31 is 69.
The number halfway between 7 and 31 is 19.
49
81 - 50 = 31 50 - 19 = 31
31
39
The next number in the sequence 5-7-13-31 is 69.
The next number is 46. The sequence adds an increasing multiple of 3. 1+3 = 4, 4+6=10, 10+9=19, 19+12=31, and 31+15 = 46. With 1 as the value for n=1, the value for the nth term is x = 1.5 n² - 1.5n + 1 e.g. the 6th term is 1.5 (6x6) - 1.5 (6) + 1 = 54 - 9 + 1 = 46
a
The number halfway between 7 and 31 is 19.
31
31
49
12 more than 19 means that you add 12 to 19 and you get 31.
Potassium-31 has 19 protons, 19 electrons, and 12 neutrons. This can be determined by looking at the atomic number of potassium (which is 19) to find the number of protons and electrons, and subtracting the atomic number from the mass number to find the number of neutrons.
81 - 50 = 31 50 - 19 = 31