我區(qū)很多學校開展了大課間活動.某校初三(1)班抽查了10名同學每分鐘仰臥起坐的次數(shù),數(shù)據(jù)如下(單位:次):51,69,64,52,64,72,48,52,76,52.
(1)這組數(shù)據(jù)的眾數(shù)為 ______;求這組數(shù)據(jù)的中位數(shù);
(2)在對初三(2)班10名同學每分鐘仰臥起坐次數(shù)的抽查中,已知這組數(shù)據(jù)的平均數(shù)正好與初三(1)班上述數(shù)據(jù)的平均數(shù)相同,且除眾數(shù)(唯一)之外的6個數(shù)之和為348.求這組數(shù)據(jù)的眾數(shù).
【答案】
分析:(1)出現(xiàn)次數(shù)最多的數(shù)為這組數(shù)據(jù)的眾數(shù),排序后位于中間兩數(shù)的平均數(shù)為該組數(shù)據(jù)的中位數(shù);
(2)先計算該組數(shù)據(jù)的平均數(shù),然后利用已知條件設出眾數(shù)列出方程解之即可.
解答:解:(1) 52;
這組數(shù)據(jù)從小到大重新排列為:
48,51,52,52,52,64,64,69,72,76.
∵居中的兩個數(shù)分別為:52和64,
(52+64)÷2=58,
∴這組數(shù)據(jù)的中位數(shù)為58;
(2)三(1)數(shù)據(jù)的平均數(shù)為:
=
(48+51+52+52+52+64+64+69+72+76)=60.
設三(2)班數(shù)據(jù)的眾數(shù)為x,
由題意得:4x+348=10×60,
解得x=63,
∴這組數(shù)據(jù)的眾數(shù)為63.
點評:本題考查了眾數(shù)、中位數(shù)的相關知識,在解決第二問時,先求出平均數(shù),然后根據(jù)題目已知條件設出未知數(shù)列出方程解得即可.