Complete Group C: Unravel the Sequence Pattern

A sequence represents the division of boys and girls into groups and is structured according to a term-to-term rule.

Complete group C.

Video Solution

Solution Steps

00:00 Complete group C

00:04 Find the difference between all girls' groups

00:14 Calculate the difference from group B to C

00:19 This is the number of girls in group C

00:27 Use the same method to find the number of boys in group C

00:32 Find the difference between all boys' groups

00:38 Calculate the difference from group B to C

00:41 This is the number of boys in group C

00:45 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we need to recognize the patterns for both boys and girls across the groups:

For the boys: The sequence given is 5, 9, 17, 21, 25 for groups A, B, D, E, F respectively. Observing the differences: $9 - 5 = 4$ , $17 - 9 = 8$ , $21 - 17 = 4$ , $25 - 21 = 4$ . This means the sequence is increasing by alternating values of 4 and 8. Thus, the missing number for group C (after 9) should be $9 + 8 = 17$ .
For the girls: The sequence given is 25, 21, 13, 9, 5. Observing the differences: $21 - 25 = -4$ , $13 - 21 = -8$ , $9 - 13 = -4$ , $5 - 9 = -4$ . This means the sequence is decreasing by alternating values of -4 and -8. Thus, the missing number for group C (after 21) should be $21 - 8 = 13$ .

Therefore, the values for group C are:

13, 17