Question

В магазине канцтовары в первой половине дня 30 человек покупали школьные тетради. 19 человек покупали только тетради в клетку а 18 человек покупали только в линейку. были ли среди 30 покупателей те которые покупали тетради двух видов. если да то сколько таких покупателей было . решение с пояснением.

Answer 1

19+18=37
37-30=7
Да были такие покупатели их было 7

Answer 2

Problem Analysis

We are given that in a stationery store, 30 people bought school notebooks in the first half of the day. Out of these, 19 people bought only grid notebooks, and 18 people bought only lined notebooks. We need to determine if there were any customers who bought both types of notebooks, and if so, how many.

Solution

To solve this problem, we can use a Venn diagram to visualize the different groups of customers. Let's represent the set of customers who bought grid notebooks as A, the set of customers who bought lined notebooks as B, and the set of customers who bought both types of notebooks as C.

From the given information, we know that: - The total number of customers who bought grid notebooks (A) is 19. - The total number of customers who bought lined notebooks (B) is 18. - The total number of customers who bought notebooks (A ∪ B) is 30.

To find the number of customers who bought both types of notebooks (C), we can use the formula: C = A + B - (A ∪ B)

Let's calculate the value of C.

Calculation

Given: - A = 19 (customers who bought grid notebooks) - B = 18 (customers who bought lined notebooks) - A ∪ B = 30 (total customers who bought notebooks)

Using the formula: C = A + B - (A ∪ B)

Substituting the values: C = 19 + 18 - 30

Calculating: C = 37 - 30 C = 7

Answer

There were 7 customers who bought both grid and lined notebooks out of the 30 customers who bought notebooks in the store.

Explanation

Out of the 30 customers who bought notebooks, 19 bought only grid notebooks, and 18 bought only lined notebooks. The remaining 7 customers bought both types of notebooks. This can be visualized using a Venn diagram, where the intersection of the two sets represents the customers who bought both types of notebooks.

Please let me know if anything is unclear or if you need further assistance!