Among the following, identify the continuous type of data :

Concept: A statistical variable is classified by the set of values it is able to assume. A variable that arises from counting indivisible units can take only isolated values, so between two neighbouring values nothing at all can be recorded. A variable that arises from measurement on a scale takes every value in an interval, so between any two of its values another value always exists, and only the precision of the instrument decides how finely it is written down.

Application: Test each choice by asking how a single value of it is produced.

• Number of languages a person speaks is produced by listing the separate languages that person can use and totalling the list, so a speaker stands at 2 languages or at 3.

• Number of children in a household is produced by enumerating the individual children living in that home, so a home stands at 2 children or at 3.

• Population of cities is produced by a census enumeration of individual residents, so a city stands at 12,50,000 residents or at 12,50,001.

• Weight of students in a class is produced by reading a weighing scale, so a student may read 48 kg, then 48.4 kg on a finer scale, then 48.37 kg on a finer scale still.

Cross-check: Set the four quantities side by side and compare how each value is produced.

Three of the quantities are counts of whole units, so their values are isolated points and the data are discrete. Only the weight of students in a class is a measurement that fills an interval. The continuous type of data among the given choices is therefore the weight of students in a class.