Below are sets of consecutive numbers, or intervals, from frequency distributions for continuous variables. For the second number, or interval, in each set, the one in bold, identify the real lower limit, real upper limit, interval width, and midpoint.
a. 27–30; 31–34; 35–38
b. 10–20; 30–40; 50–60
c. 2.00–2.49; 2.50–2.99; 3.00–3.49
d. 10; 11; 12